path: root/2023/info/test-after.md

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# Transcript


Introduction

[[!template new="1" text="""Hi everyone! I'm Mats Lidell.""" start="00:00:03.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""I'm going to talk about my journey""" start="00:00:07.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""writing test cases for GNU Hyperbole""" start="00:00:09.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""and what I learned on the way.""" start="00:00:12.481" video="mainVideo-test" id="subtitle"]]
[[!template text="""So, why write tests for GNU Hyperbole?""" start="00:00:19.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""There is some background.""" start="00:00:24.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""I'm the co-maintainer of GNU Hyperbole""" start="00:00:25.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""together with Bob Weiner. Bob is the author of the package.""" start="00:00:27.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""The package is available through""" start="00:00:33.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""the Emacs package manager and GNU Elpa""" start="00:00:34.681" video="mainVideo-test" id="subtitle"]]
[[!template text="""if you would want to try it out.""" start="00:00:38.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""The package has some age. I think it dates back to""" start="00:00:42.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""a first release around 1993, which is also""" start="00:00:46.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""when I got in contact with the package the first time.""" start="00:00:50.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""I was a user of the package for many years.""" start="00:00:54.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""Later, I became the maintainer of the package for the FSF.""" start="00:00:58.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""That was although I did not have""" start="00:01:03.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""much knowledge of Emacs Lisp,""" start="00:01:04.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""and I still have a lot to learn.""" start="00:01:09.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""A few years ago, we started to work actively on the package,""" start="00:01:12.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""with setting up goals and having meetings.""" start="00:01:15.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""So my starting point is that I had experience""" start="00:01:20.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""with test automation from development""" start="00:01:24.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""in C++, Java and Python""" start="00:01:27.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""using different x-unit frameworks like cppunit, junit.""" start="00:01:30.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""That was in my daytime work where""" start="00:01:37.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""the technique of using pull requests""" start="00:01:40.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""with changes backed up by tests were the daily routine.""" start="00:01:41.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""It was really a requirement for a change to go in""" start="00:01:46.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""to have supporting test cases.""" start="00:01:49.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""I believe, a quite common setup and requirement these days.""" start="00:01:52.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""I also had been an Emacs user for many years,""" start="00:01:58.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""but with focus on being a user.""" start="00:02:02.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""So as I mentioned, I have limited Emacs Lisp knowledge.""" start="00:02:04.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""When we decided to start""" start="00:02:09.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""to work actively on Hyperbole again,""" start="00:02:11.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""it was natural for me to look into""" start="00:02:13.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""raising the quality by adding unit tests.""" start="00:02:15.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""This also goes hand in hand""" start="00:02:18.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""with running these regularly as part of a build process.""" start="00:02:20.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""All in all, following the current best practice""" start="00:02:25.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""of software development.""" start="00:02:28.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""But since Hyperbole had no tests at all,""" start="00:02:31.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""it would not be enough just to add tests""" start="00:02:36.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""for new or changed functionality.""" start="00:02:38.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""We wanted to add it even broader; ideally, everywhere.""" start="00:02:41.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""So work started with adding tests here and there""" start="00:02:44.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""based on our gut feeling where it would be most useful.""" start="00:02:48.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""This work is still ongoing.""" start="00:02:52.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""So this is where my journey starts""" start="00:02:55.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""with much functionality to test,""" start="00:02:58.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""no knowledge of what testing frameworks existed,""" start="00:03:00.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""and not really knowing a lot about Emacs Lisp at all.""" start="00:03:03.360" video="mainVideo-test" id="subtitle"]]

ERT: Emacs Lisp Regression Testing

[[!template new="1" text="""Luckily there is a package for writing tests in Emacs.""" start="00:03:11.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""It is called ERT: Emacs Lisp Regression Testing.""" start="00:03:13.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""It contains both support for defining tests and running them.""" start="00:03:17.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""Defining a test is done with the macro `ert-deftest`.""" start="00:03:20.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""In its simplest form, a test has a name, a doc string, and a body.""" start="00:03:24.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""The doc string is where you typically can give""" start="00:03:28.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""a detailed description of the test""" start="00:03:31.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""and has space for more info""" start="00:03:33.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""than what can be given in the test name.""" start="00:03:35.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""The body is where all the interesting things happen.""" start="00:03:42.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""It is here you prepare the test, run it and verify the outcome.""" start="00:03:45.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""Schematically, it looks like this.""" start="00:03:51.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""You have the ert-deftest, you have the test name,""" start="00:03:54.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""and the doc string, and then the body.""" start="00:04:00.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""It is in the body where everything interesting happens.""" start="00:04:02.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""The test is prepared, the function of the test is executed,""" start="00:04:06.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""and the outcome of the test is evaluated.""" start="00:04:09.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""Did the test succeed or not?""" start="00:04:13.120" video="mainVideo-test" id="subtitle"]]

Assertions with `should`

[[!template new="1" text="""The verification of a test is performed with""" start="00:04:14.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""one or more so-called assertions.""" start="00:04:18.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""In ERT, they are implemented""" start="00:04:21.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""with the macro `should`""" start="00:04:25.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""together with a set of related macros.""" start="00:04:26.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""`should` takes a form as argument,""" start="00:04:33.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""and if the form evaluates to nil,""" start="00:04:35.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""the test has failed. So let's look at an example.""" start="00:04:37.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""This simple test verifies that the function `+`""" start="00:04:48.581" video="mainVideo-test" id="subtitle"]]
[[!template text="""can add the numbers 2 and 3 and get the result 5.""" start="00:04:51.920" video="mainVideo-test" id="subtitle"]]

Running a test case

[[!template new="1" text="""So now we have defined a test case. How do we run it?""" start="00:04:56.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""The ERT package has the function (or""" start="00:05:01.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""rather convenience alias) `ert`. It takes a test selector.""" start="00:05:03.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""The test name works as a selector for running just one test.""" start="00:05:09.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""So here we have the example. Let's evaluate it.""" start="00:05:19.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""We define it and then we run it using ERT.""" start="00:05:27.901" video="mainVideo-test" id="subtitle"]]
[[!template text="""As you see, we get prompted for a test selector""" start="00:05:34.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""but we only have one test case defined at the moment.""" start="00:05:42.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""It's the example 0. So let's hit RET.""" start="00:05:46.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""As you see here, we get some output""" start="00:05:55.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""describing what we have just done.""" start="00:05:58.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""There is one test case it has passed, zero failed,""" start="00:06:01.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""zero skipped, total 1 of 1 test case""" start="00:06:04.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""and some time stamps for the execution.""" start="00:06:07.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""We also see this green mark here indicating one test case""" start="00:06:14.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""and that it was successful.""" start="00:06:18.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""For inspecting the test, we can hit the letter `l`""" start="00:06:23.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""which shows all the `should` forms""" start="00:06:29.660" video="mainVideo-test" id="subtitle"]]
[[!template text="""that was executed during this test case.""" start="00:06:32.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""So here we see that we have the `should`,""" start="00:06:37.780" video="mainVideo-test" id="subtitle"]]
[[!template text="""one `should` executed, and we see the form equals to 2,""" start="00:06:39.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""and it was 5 equals to 5.""" start="00:06:48.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""So a good example of a successful test case.""" start="00:06:49.800" video="mainVideo-test" id="subtitle"]]

Debug a test

[[!template new="1" text="""So now we've seen how we can run a test case.""" start="00:06:54.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""Can we debug it? Yes. For debugging a test case,""" start="00:06:57.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""the `ert-deftest` can be set up using `edebug-defun`,""" start="00:07:03.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""just as a function or macro is set up""" start="00:07:07.940" video="mainVideo-test" id="subtitle"]]
[[!template text="""or instrumented for debugging. So let's try that.""" start="00:07:10.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""So we try `edebug-defun` here.""" start="00:07:18.820" video="mainVideo-test" id="subtitle"]]
[[!template text="""Now it's instrumented for debugging.""" start="00:07:24.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""And we run it, `ert`, and we're inside the debugger,""" start="00:07:28.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""and we can inspect here what's happening.""" start="00:07:35.660" video="mainVideo-test" id="subtitle"]]
[[!template text="""Step through it and yes it succeeded just as before.""" start="00:07:40.680" video="mainVideo-test" id="subtitle"]]

Commercial break: Hyperbole

[[!template new="1" text="""It's time for a commercial break!""" start="00:07:50.380" video="mainVideo-test" id="subtitle"]]
[[!template text="""Hyperbole itself can help with running tests""" start="00:07:56.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""and also help with running them in debug mode.""" start="00:08:00.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""That is because hyperbole identifies the `ert-deftest`""" start="00:08:03.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""as an implicit button. An implicit button is basically""" start="00:08:08.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""a string or pattern""" start="00:08:12.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""that Hyperbole has assigned some meaning to.""" start="00:08:13.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""For the string `ert-deftest`, it is to run the test case.""" start="00:08:16.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""You activate the button with the action-key.""" start="00:08:19.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""The standard binding is the middle mouse button,""" start="00:08:24.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""or from the keyboard, M-RET.""" start="00:08:27.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""So let's try that.""" start="00:08:33.041" video="mainVideo-test" id="subtitle"]]
[[!template text="""We move the cursor here and then we type M-RET.""" start="00:08:34.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""And boom, the test case was executed.""" start="00:08:42.220" video="mainVideo-test" id="subtitle"]]
[[!template text="""And to run it in debug mode we type C-u M-RET""" start="00:08:47.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""to get the assist key, and then we're in the debugger.""" start="00:08:54.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""So that's pretty useful and convenient.""" start="00:08:57.720" video="mainVideo-test" id="subtitle"]]

Instrument function on the fly

[[!template new="1" text="""A related useful feature here is the step-in functionality""" start="00:09:10.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""bound to the letter i in `debug-mode`.""" start="00:09:13.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""It allows you to step into a function""" start="00:09:16.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""and continue debugging from there.""" start="00:09:18.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""For the cases where your test does not do what you want,""" start="00:09:20.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""looking at what happens in the function of the test""" start="00:09:22.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""can be really useful. Let's try that with another example.""" start="00:09:25.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""So here we have two helper functions, one `f1-add`,""" start="00:09:37.260" video="mainVideo-test" id="subtitle"]]
[[!template text="""that use the built-in `+` function""" start="00:09:43.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""and then we have `my-add` that uses that function.""" start="00:09:47.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""So we're going to test myadd.""" start="00:09:52.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""And then let's run this.""" start="00:09:59.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""Let's run this using hyperbole in debug mode""" start="00:10:02.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""C-u M-RET. We're in the debugger again,""" start="00:10:05.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""and let's step up front to my function under test""" start="00:10:10.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""and then press `i` for getting it instrumented""" start="00:10:15.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""and going into it for debugging.""" start="00:10:19.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""And here we can expect that it's getting""" start="00:10:23.020" video="mainVideo-test" id="subtitle"]]
[[!template text="""the arguments 1 and 3,""" start="00:10:25.140" video="mainVideo-test" id="subtitle"]]
[[!template text="""and it returns the result 4 as expected.""" start="00:10:26.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""And yes, of course, our test case will then succeed.""" start="00:10:31.000" video="mainVideo-test" id="subtitle"]]

Mocking

[[!template new="1" text="""The next tool in our toolbox is mocking.""" start="00:10:39.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""Mocking is needed when we want to simulate the response""" start="00:10:41.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""from a function used by the function under test.""" start="00:10:46.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""That is the implementation of the function.""" start="00:10:49.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""This could be for various reasons.""" start="00:10:53.140" video="mainVideo-test" id="subtitle"]]
[[!template text="""One example could be because it would be hard or impossible""" start="00:10:56.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""in the test setup to get the behavior you want to test for,""" start="00:11:00.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""like an external error case.""" start="00:11:04.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""But the mock can also be used to verify""" start="00:11:06.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""that the function is called with a specific argument.""" start="00:11:08.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""We can view it as a way to isolate the function on the test""" start="00:11:11.620" video="mainVideo-test" id="subtitle"]]
[[!template text="""from its dependencies.""" start="00:11:14.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""So in order to test the function in isolation,""" start="00:11:16.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""we need to cut out any dependencies to external behavior.""" start="00:11:18.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""Most obvious would be dependencies to external resources,""" start="00:11:22.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""such as web pages. As an example:""" start="00:11:25.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""Hyperbole contains functionality to link you to""" start="00:11:27.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""social media resources and other resources on the net.""" start="00:11:30.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""Testing that would require the test system to call out""" start="00:11:34.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""to the social media resources""" start="00:11:37.900" video="mainVideo-test" id="subtitle"]]
[[!template text="""and would depend on it being available, etc.""" start="00:11:39.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""Nothing technically stops a test case""" start="00:11:43.540" video="mainVideo-test" id="subtitle"]]
[[!template text="""to depend on the external resources,""" start="00:11:45.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""but would, if nothing else, be flaky or slow.""" start="00:11:47.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""It could be part of an end-to-end suite""" start="00:11:51.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""where we want to test that it works all the way.""" start="00:11:53.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""In this case, we want to look at the isolated case""" start="00:11:57.180" video="mainVideo-test" id="subtitle"]]
[[!template text="""that can be run with no dependency on external resources.""" start="00:11:59.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""What you want to do is to replace the function with a mock""" start="00:12:04.100" video="mainVideo-test" id="subtitle"]]
[[!template text="""that behaves as the real function would do.""" start="00:12:06.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""The package I have found""" start="00:12:10.340" video="mainVideo-test" id="subtitle"]]
[[!template text="""and have used for mocking is `el-mock`.""" start="00:12:11.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""The workhorse in this package is the `with-mock` macro.""" start="00:12:14.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""It looks like this: `with-mock` followed by a body.""" start="00:12:21.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""In the execution of the body, stubs and mocks""" start="00:12:26.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""defined in the body is respected.""" start="00:12:30.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""Let's look at some examples to make that clearer.""" start="00:12:32.900" video="mainVideo-test" id="subtitle"]]
[[!template text="""In this case, we have the macro `with-mock`.""" start="00:12:39.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""It works so that the expression""" start="00:12:42.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""`stub + => 10` is interpreted""" start="00:12:43.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""so that the function `+` will be replaced with the stub.""" start="00:12:48.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""The stub will return 10 regardless how it is called.""" start="00:12:51.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""Note that the stub function""" start="00:12:56.780" video="mainVideo-test" id="subtitle"]]
[[!template text="""does not have to be called at this level""" start="00:12:58.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""but could be called at any level in the call chain.""" start="00:13:00.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""By knowing how the function under test is implemented""" start="00:13:02.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""and how the implementation works,""" start="00:13:07.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""you can find function calls you want to mock""" start="00:13:09.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""to force certain behavior that you want to test,""" start="00:13:11.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""or to avoid calls to external resources, slow calls, etc.""" start="00:13:15.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""Simply isolate the function under test""" start="00:13:19.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""and simulate its environment.""" start="00:13:21.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""Mock is a little bit more sophisticated""" start="00:13:26.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""and depends on the arguments""" start="00:13:28.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""that the mock function is called with.""" start="00:13:30.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""Or more precise, it is checked""" start="00:13:31.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""after the `with-mock` clause""" start="00:13:33.848" video="mainVideo-test" id="subtitle"]]
[[!template text="""that the arguments match the arguments it was called with""" start="00:13:35.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""or even if it was called at all.""" start="00:13:38.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""If it is called with other arguments""" start="00:13:39.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""there will be an error,""" start="00:13:41.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""and if it's not called, it is also an error.""" start="00:13:43.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""So this way, we are sure that the function""" start="00:13:46.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""we were expected to be called actually was called.""" start="00:13:48.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""An important piece of the testing.""" start="00:13:51.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""So we are sure that the mock we have provided""" start="00:13:53.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""actually is triggered by the test case.""" start="00:13:56.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""So here we have an example of `with-mock`""" start="00:14:04.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""where the `f1-add` function is mocked,""" start="00:14:08.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""so that if it's called with 2 and 3 as arguments,""" start="00:14:18.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""it will return 10. Then we have a test case""" start="00:14:22.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""where we try the `my-add` function,""" start="00:14:24.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""as you might remember, and call that with 2 and 3""" start="00:14:28.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""and see that it should also then return 10""" start="00:14:30.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""because it's using `f1-add`.""" start="00:14:32.800" video="mainVideo-test" id="subtitle"]]

cl-letf

[[!template new="1" text="""Moving over to `cl-letf`.""" start="00:14:41.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""In rare occasions, the limitations of `el-mock` means""" start="00:14:44.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""you would want to implement a full-fledged function""" start="00:14:47.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""to be used under test.""" start="00:14:50.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""Then the macro `cl-letf` can be useful.""" start="00:14:52.980" video="mainVideo-test" id="subtitle"]]
[[!template text="""However, you need to handle the case yourself""" start="00:14:55.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""if the function was not called.""" start="00:14:57.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""Looking through the test cases where I have used `cl-letf`,""" start="00:15:00.100" video="mainVideo-test" id="subtitle"]]
[[!template text="""I think most can be implemented using plain mocking.""" start="00:15:03.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""Cases left is where the args to the mock might be different""" start="00:15:06.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""due to environment issues.""" start="00:15:11.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""In that case, a static mock will not work.""" start="00:15:13.740" video="mainVideo-test" id="subtitle"]]

Hooks

[[!template new="1" text="""Another trick is that functions that uses hooks.""" start="00:15:24.100" video="mainVideo-test" id="subtitle"]]
[[!template text="""You can overload or replace the hooks to do the testing.""" start="00:15:30.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""So you can use the hook function just to do the verification""" start="00:15:35.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""and not do anything useful in the hook.""" start="00:15:40.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""Also, here you need to be careful""" start="00:15:43.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""to make sure the test handler is called and nothing else.""" start="00:15:45.080" video="mainVideo-test" id="subtitle"]]

Side effects and initial buffer state

[[!template new="1" text="""So far we have been talking about testing""" start="00:15:55.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""and what the function returns.""" start="00:15:57.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""In the best of words, we have a pure function""" start="00:15:59.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""that only depends on its arguments""" start="00:16:01.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""and produces no side effects.""" start="00:16:02.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""Many operations produce side effects""" start="00:16:04.940" video="mainVideo-test" id="subtitle"]]
[[!template text="""or operate on the contents of buffers""" start="00:16:06.900" video="mainVideo-test" id="subtitle"]]
[[!template text="""such as writing a message in the message buffer,""" start="00:16:09.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""change the state of a buffer, move point etc.""" start="00:16:12.380" video="mainVideo-test" id="subtitle"]]
[[!template text="""Hyperbole is not an exception. Quite the contrary.""" start="00:16:15.660" video="mainVideo-test" id="subtitle"]]
[[!template text="""Much of the functions creating links""" start="00:16:18.860" video="mainVideo-test" id="subtitle"]]
[[!template text="""are just about updating buffers.""" start="00:16:20.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""This poses a special problem for tests.""" start="00:16:24.421" video="mainVideo-test" id="subtitle"]]
[[!template text="""The test gets longer""" start="00:16:28.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""since you need to create buffers and files,""" start="00:16:29.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""initialize the contents.""" start="00:16:31.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""Verifying the outcome becomes trickier""" start="00:16:33.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""since you need to make sure you look at the right place.""" start="00:16:35.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""At the end of the test, you need to clean up,""" start="00:16:39.020" video="mainVideo-test" id="subtitle"]]
[[!template text="""both for not leaving a lot of garbage""" start="00:16:41.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""in buffers and files around,""" start="00:16:43.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""and even worse, not cause later tests""" start="00:16:45.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""to depend on the leftovers from the other tests.""" start="00:16:48.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""Here are some functions and variables""" start="00:16:50.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""I have found useful for this.""" start="00:16:53.080" video="mainVideo-test" id="subtitle"]]

with-temp-buffer

[[!template new="1" text="""For creating tests: `with-temp-buffer`:""" start="00:17:05.100" video="mainVideo-test" id="subtitle"]]
[[!template text="""it provides you a temp buffer that you visit,""" start="00:17:09.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""and afterwards, there is no need to clean up.""" start="00:17:11.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""This is the first choice if that is all you need.""" start="00:17:13.720" video="mainVideo-test" id="subtitle"]]

make-temp-file

[[!template new="1" text="""`make-temp-file`: If you need a file,""" start="00:17:16.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""this is the function to use.""" start="00:17:20.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""It creates a temp file or a directory.""" start="00:17:21.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""The file can be filled with initial contents.""" start="00:17:24.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""This needs to be cleaned up after a test.""" start="00:17:26.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""Moving on to verifying and debugging:""" start="00:17:31.020" video="mainVideo-test" id="subtitle"]]

buffer-string

[[!template new="1" text="""`buffer-string`: returns the full contents""" start="00:17:33.288" video="mainVideo-test" id="subtitle"]]
[[!template text="""of the buffer as a string.""" start="00:17:38.248" video="mainVideo-test" id="subtitle"]]
[[!template text="""That can sound a bit voluminous,""" start="00:17:39.500" video="mainVideo-test" id="subtitle"]]
[[!template text="""but since tests are normally small, this often works well.""" start="00:17:41.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""I have in particular found good use of comparing""" start="00:17:46.140" video="mainVideo-test" id="subtitle"]]
[[!template text="""the contents of buffers with the empty string.""" start="00:17:48.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""That would give an error, but as we have seen""" start="00:17:50.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""with the output produced by the `should` assertion,""" start="00:17:53.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""this is almost like a print statement""" start="00:17:56.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""and can be compared with the good old technique""" start="00:17:58.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""of debugging with print statements.""" start="00:18:01.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""There might be other ways to do the same""" start="00:18:04.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""as we saw with debugging.""" start="00:18:06.248" video="mainVideo-test" id="subtitle"]]

buffer-name

[[!template new="1" text="""buffer-name: Getting the buffer name is good""" start="00:18:09.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""to verify what buffer we are looking at.""" start="00:18:13.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""I often found it useful to check""" start="00:18:16.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""that my assumptions on what buffer I am acting on""" start="00:18:18.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""is correct by adding `should` clauses""" start="00:18:21.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""in the middle of the test execution""" start="00:18:23.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""or after preparing the test input.""" start="00:18:25.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""Sometimes Emacs can switch buffers in strange ways,""" start="00:18:27.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""maybe because the test case is badly written,""" start="00:18:31.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""and making sure your assumptions are correct""" start="00:18:34.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""is a good sanity check.""" start="00:18:37.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""Even the ert package does""" start="00:18:40.340" video="mainVideo-test" id="subtitle"]]
[[!template text="""some buffer and windows manipulation for its reporting""" start="00:18:42.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""that I have not fully learned how to master,""" start="00:18:44.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""so assertion for checking the sanity of the test is good.""" start="00:18:47.488" video="mainVideo-test" id="subtitle"]]

major-mode

[[!template new="1" text="""Finally, `major-mode`: Verify the buffer has the proper mode.""" start="00:18:51.980" video="mainVideo-test" id="subtitle"]]
[[!template text="""Can also be very useful and is a good sanity check.""" start="00:18:55.680" video="mainVideo-test" id="subtitle"]]

unwind-protect

[[!template new="1" text="""Finally, cleaning up. `unwind-protect`.""" start="00:19:02.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""The tool for cleaning up is the `unwind-protect` form""" start="00:19:06.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""which ensures that the unwind forms""" start="00:19:09.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""always are executed regardless of the outcome of the body.""" start="00:19:12.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""So if your test fails, you are sure the cleanup is executed.""" start="00:19:15.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""Let's look at unwind-protect together with""" start="00:19:20.420" video="mainVideo-test" id="subtitle"]]
[[!template text="""the temporary file example. Many tests look like this.""" start="00:19:22.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""You create some resource, you call `unwind-protect`,""" start="00:19:30.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""you do the test, and then afterwards you do the cleanup.""" start="00:19:35.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""The cleanup for a file and a buffer is so common,""" start="00:19:42.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""so I have created a helper for that.""" start="00:19:46.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""It looks like this.""" start="00:19:51.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""The trick with the `buffer-modified` flag""" start="00:19:56.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""is to avoid getting prompted""" start="00:19:59.180" video="mainVideo-test" id="subtitle"]]
[[!template text="""for killing a buffer that is not saved.""" start="00:20:00.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""The test buffers are often in the state""" start="00:20:03.220" video="mainVideo-test" id="subtitle"]]
[[!template text="""where they have not been saved but modified.""" start="00:20:05.440" video="mainVideo-test" id="subtitle"]]

Input, with-simulated-input

[[!template new="1" text="""Another problem for tests are input.""" start="00:20:15.100" video="mainVideo-test" id="subtitle"]]
[[!template text="""In the middle of execution a function""" start="00:20:19.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""might want to have some interaction with the user.""" start="00:20:21.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""Testing this poses a problem, not only in that""" start="00:20:24.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""the input matters, but also as how even to get the test case""" start="00:20:26.960" video="mainVideo-test" id="subtitle"]]
[[!template text="""to recognize the input!?""" start="00:20:31.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""Ideally the tests are run in batch mode,""" start="00:20:34.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""which in some sense means no user interaction.""" start="00:20:36.040" video="mainVideo-test" id="subtitle"]]
[[!template text="""In batch mode, there is no event loop running.""" start="00:20:38.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""Fortunately, there is a package `with-simulated-input`""" start="00:20:43.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""that gets you around these issues.""" start="00:20:47.180" video="mainVideo-test" id="subtitle"]]
[[!template text="""This is a macro that allows us""" start="00:20:53.260" video="mainVideo-test" id="subtitle"]]
[[!template text="""to define a set of characters""" start="00:20:55.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""that will be read by the function under the test,""" start="00:20:57.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""and all of this works in batch mode. It looks like this.""" start="00:20:59.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""We have `with-simulated-input`,""" start="00:21:02.580" video="mainVideo-test" id="subtitle"]]
[[!template text="""and then a string of characters, and then a body.""" start="00:21:04.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""The form takes a string of keys""" start="00:21:09.840" video="mainVideo-test" id="subtitle"]]
[[!template text="""and runs the rest of the body,""" start="00:21:11.648" video="mainVideo-test" id="subtitle"]]
[[!template text="""and if there are input required,""" start="00:21:13.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""it is picked from the string of keys.""" start="00:21:15.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""In our example, the `read-string` call""" start="00:21:18.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""will read up until RET,""" start="00:21:20.422" video="mainVideo-test" id="subtitle"]]
[[!template text="""and then return the characters read.""" start="00:21:21.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""As you see in the example, space needs to be provided""" start="00:21:26.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""by the string SPC, as return by the string RET.""" start="00:21:29.640" video="mainVideo-test" id="subtitle"]]

Running all tests

[[!template new="1" text="""So now we have seen ways to create test cases""" start="00:21:38.460" video="mainVideo-test" id="subtitle"]]
[[!template text="""and even make it possible to run some of them""" start="00:21:40.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""that has I/O in batch mode.""" start="00:21:43.220" video="mainVideo-test" id="subtitle"]]
[[!template text="""But the initial goal was to run them all at once.""" start="00:21:44.680" video="mainVideo-test" id="subtitle"]]
[[!template text="""How do you do that?""" start="00:21:47.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""Let's go back to the `ert` command.""" start="00:21:48.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""It prompts for a test selector.""" start="00:21:51.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""If we give it the selector `t`,""" start="00:21:53.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""it will run all tests we have currently defined.""" start="00:21:56.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""Let's try that with the subset of the Hyperbole tests.""" start="00:21:59.260" video="mainVideo-test" id="subtitle"]]
[[!template text="""Here is the test folder in the Hyperbole directory.""" start="00:22:05.780" video="mainVideo-test" id="subtitle"]]
[[!template text="""Let's go up here and load all the demo tests.""" start="00:22:09.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""And then try to run `ert`.""" start="00:22:18.820" video="mainVideo-test" id="subtitle"]]
[[!template text="""Now we see that we have a bunch of test cases.""" start="00:22:21.208" video="mainVideo-test" id="subtitle"]]
[[!template text="""We can all run them individually,""" start="00:22:26.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""but we can run them with `t` instead.""" start="00:22:27.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""We will run them all at once.""" start="00:22:31.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""So now, ert is executing all our test cases.""" start="00:22:35.460" video="mainVideo-test" id="subtitle"]]
[[!template text="""So here we have a nice green display""" start="00:22:51.420" video="mainVideo-test" id="subtitle"]]
[[!template text="""with all the test cases.""" start="00:22:57.080" video="mainVideo-test" id="subtitle"]]

Batch mode

[[!template new="1" text="""So that was fine, but we were still running it manually""" start="00:23:03.220" video="mainVideo-test" id="subtitle"]]
[[!template text="""by calling ert. How could we run it from the command line?""" start="00:23:08.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""Ert comes with functions for running it in batch mode.""" start="00:23:17.180" video="mainVideo-test" id="subtitle"]]
[[!template text="""For Hyperbole, we use `make` for repetitive tasks.""" start="00:23:21.500" video="mainVideo-test" id="subtitle"]]
[[!template text="""So we have a make target""" start="00:23:25.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""that uses the ert batch functionality,""" start="00:23:27.120" video="mainVideo-test" id="subtitle"]]
[[!template text="""and this is the line from the Makefile.""" start="00:23:29.280" video="mainVideo-test" id="subtitle"]]
[[!template text="""This is a bit detailed,""" start="00:23:33.260" video="mainVideo-test" id="subtitle"]]
[[!template text="""but you see that we have a part here""" start="00:23:35.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""where we load the test dependencies.""" start="00:23:37.540" video="mainVideo-test" id="subtitle"]]
[[!template text="""For getting the packages""" start="00:23:40.780" video="mainVideo-test" id="subtitle"]]
[[!template text="""such as `el-mock` and `with-simulated-input` etc. loaded.""" start="00:23:43.521" video="mainVideo-test" id="subtitle"]]
[[!template text="""We also have... I also want to point out here the call to""" start="00:23:48.460" video="mainVideo-test" id="subtitle"]]
[[!template text="""or the setting of `auto-save-default` to `nil`""" start="00:23:53.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""to get away with the prompt for excessive backup files""" start="00:23:58.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""that can pile up after running the tests a few times.""" start="00:24:02.440" video="mainVideo-test" id="subtitle"]]

Skipping tests

[[!template new="1" text="""Even with the help of simulated input,""" start="00:24:05.060" video="mainVideo-test" id="subtitle"]]
[[!template text="""not all tests can be run in batch mode.""" start="00:24:06.880" video="mainVideo-test" id="subtitle"]]
[[!template text="""They would simply not work there""" start="00:24:08.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""and have to be run in an interactive Emacs""" start="00:24:10.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""with the running event loop.""" start="00:24:12.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""One trick still to be able to use batch mode for automation""" start="00:24:14.180" video="mainVideo-test" id="subtitle"]]
[[!template text="""is to put the guard at the top of each test case""" start="00:24:17.920" video="mainVideo-test" id="subtitle"]]
[[!template text="""as the first thing to be executed,""" start="00:24:20.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""so that it kicks in before anything else and stops Emacs""" start="00:24:22.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""to try to run the test case.""" start="00:24:25.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""Now, it looks like this: `(skip-unless (not noninteractive))`.""" start="00:24:27.200" video="mainVideo-test" id="subtitle"]]
[[!template text="""So when ert sees that the test should be skipped, it skips it""" start="00:24:35.520" video="mainVideo-test" id="subtitle"]]
[[!template text="""and makes a note of that,""" start="00:24:38.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""so you will see how many tests that have been skipped.""" start="00:24:40.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""Too bad. We have a number of test cases defined,""" start="00:24:44.580" video="mainVideo-test" id="subtitle"]]
[[!template text="""and to run them, we need to run them manually. Well sort of.""" start="00:24:47.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""Not being able to run all tests easily""" start="00:24:51.360" video="mainVideo-test" id="subtitle"]]
[[!template text="""is a bit counterproductive""" start="00:24:53.808" video="mainVideo-test" id="subtitle"]]
[[!template text="""since our goal is to run all tests.""" start="00:24:58.420" video="mainVideo-test" id="subtitle"]]
[[!template text="""There is however no ert function to run tests in batch mode""" start="00:25:01.000" video="mainVideo-test" id="subtitle"]]
[[!template text="""with an interactive Emacs.""" start="00:25:04.720" video="mainVideo-test" id="subtitle"]]
[[!template text="""The closest I have got is either""" start="00:25:06.780" video="mainVideo-test" id="subtitle"]]
[[!template text="""to start the Emacs from the command line""" start="00:25:08.480" video="mainVideo-test" id="subtitle"]]
[[!template text="""calling the ert function as we just have seen,""" start="00:25:10.080" video="mainVideo-test" id="subtitle"]]
[[!template text="""and then killing it manually when done;""" start="00:25:12.440" video="mainVideo-test" id="subtitle"]]
[[!template text="""or add a function to extract the contents of the ERT buffer""" start="00:25:14.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""when done and echo it to standard output.""" start="00:25:19.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""This is how it looks in the Makefile""" start="00:25:24.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""to get the behavior of cutting and paste,""" start="00:25:27.801" video="mainVideo-test" id="subtitle"]]
[[!template text="""getting the ERT output into a file""" start="00:25:31.208" video="mainVideo-test" id="subtitle"]]
[[!template text="""so we can then kill Emacs""" start="00:25:34.581" video="mainVideo-test" id="subtitle"]]
[[!template text="""and spit out the content of the ERT buffer.""" start="00:25:36.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""One final word here is that""" start="00:25:44.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""when you run this in a continuous integration pipeline,""" start="00:25:47.740" video="mainVideo-test" id="subtitle"]]
[[!template text="""you might not have a TTY for getting Emacs to start,""" start="00:25:54.560" video="mainVideo-test" id="subtitle"]]
[[!template text="""and that is then another problem""" start="00:25:59.400" video="mainVideo-test" id="subtitle"]]
[[!template text="""with getting the interactive mode.""" start="00:26:03.201" video="mainVideo-test" id="subtitle"]]

Conclusion

[[!template new="1" text="""We have reached the end of the talk.""" start="00:26:08.460" video="mainVideo-test" id="subtitle"]]
[[!template text="""If you have any new ideas""" start="00:26:11.121" video="mainVideo-test" id="subtitle"]]
[[!template text="""or have some suggestions for improvements,""" start="00:26:14.160" video="mainVideo-test" id="subtitle"]]
[[!template text="""feel free to reach out""" start="00:26:16.760" video="mainVideo-test" id="subtitle"]]
[[!template text="""because I am still on the learning curve of writing,""" start="00:26:18.240" video="mainVideo-test" id="subtitle"]]
[[!template text="""how to write good test cases.""" start="00:26:21.101" video="mainVideo-test" id="subtitle"]]
[[!template text="""If you look at the test cases we have in Hyperbole""" start="00:26:25.300" video="mainVideo-test" id="subtitle"]]
[[!template text="""and you think they might contradict what I am saying here,""" start="00:26:27.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""it is OK. It is probably right.""" start="00:26:29.800" video="mainVideo-test" id="subtitle"]]
[[!template text="""I have changed the style as I go""" start="00:26:32.580" video="mainVideo-test" id="subtitle"]]
[[!template text="""and we have not yet refactored all tests""" start="00:26:34.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""to benefit from new designs.""" start="00:26:36.640" video="mainVideo-test" id="subtitle"]]
[[!template text="""That is also the beauty of the test case.""" start="00:26:38.580" video="mainVideo-test" id="subtitle"]]
[[!template text="""As long as it serves its purpose, it is not terrible""" start="00:26:40.600" video="mainVideo-test" id="subtitle"]]
[[!template text="""if it is not optimal or not having the best style.""" start="00:26:43.320" video="mainVideo-test" id="subtitle"]]
[[!template text="""And yes, thanks for listening. Bye.""" start="00:26:47.800" video="mainVideo-test" id="subtitle"]]

Questions or comments? Please e-mail [matsl@gnu.org](mailto:matsl@gnu.org?subject=Comment%20for%20EmacsConf%202023%20test%3A%20What%20I%20learned%20by%20writing%20test%20cases%20for%20GNU%20Hyperbole)


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