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diff --git a/2023/captions/emacsconf-2023-test--what-i-learned-by-writing-test-cases-for-gnu-hyperbole--mats-lidell--main--chapters.vtt b/2023/captions/emacsconf-2023-test--what-i-learned-by-writing-test-cases-for-gnu-hyperbole--mats-lidell--main--chapters.vtt
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@@ -0,0 +1,68 @@
+WEBVTT
+
+
+00:00:03.120 --> 00:03:11.159
+Introduction
+
+00:03:11.160 --> 00:04:14.359
+ERT: Emacs Lisp Regression Testing
+
+00:04:14.360 --> 00:04:56.919
+Assertions with `should`
+
+00:04:56.920 --> 00:06:54.559
+Running a test case
+
+00:06:54.560 --> 00:07:46.960
+Debug a test
+
+00:07:50.380 --> 00:09:10.479
+Commercial break: Hyperbole
+
+00:09:10.480 --> 00:10:39.119
+Instrument function on the fly
+
+00:10:39.120 --> 00:14:41.239
+Mocking
+
+00:14:41.240 --> 00:15:24.099
+cl-letf
+
+00:15:24.100 --> 00:15:55.719
+Hooks
+
+00:15:55.720 --> 00:17:05.099
+Side effects and initial buffer state
+
+00:17:05.100 --> 00:17:16.519
+with-temp-buffer
+
+00:17:16.520 --> 00:17:33.287
+make-temp-file
+
+00:17:33.288 --> 00:18:09.919
+buffer-string
+
+00:18:09.920 --> 00:18:51.979
+buffer-name
+
+00:18:51.980 --> 00:19:02.679
+major-mode
+
+00:19:02.680 --> 00:20:15.099
+unwind-protect
+
+00:20:15.100 --> 00:21:38.459
+Input, with-simulated-input
+
+00:21:38.460 --> 00:23:03.219
+Running all tests
+
+00:23:03.220 --> 00:24:05.059
+Batch mode
+
+00:24:05.060 --> 00:26:05.160
+Skipping tests
+
+00:26:08.460 --> 00:26:55.240
+Conclusion
diff --git a/2023/captions/emacsconf-2023-test--what-i-learned-by-writing-test-cases-for-gnu-hyperbole--mats-lidell--main.vtt b/2023/captions/emacsconf-2023-test--what-i-learned-by-writing-test-cases-for-gnu-hyperbole--mats-lidell--main.vtt
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--- /dev/null
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@@ -0,0 +1,1371 @@
+WEBVTT captioned by sachac, checked by sachac
+
+NOTE Introduction
+
+00:00:03.120 --> 00:00:07.439
+Hi everyone! I'm Mats Lidell.
+
+00:00:07.440 --> 00:00:09.879
+I'm going to talk about my journey
+
+00:00:09.880 --> 00:00:12.480
+writing test cases for GNU Hyperbole
+
+00:00:12.481 --> 00:00:19.399
+and what I learned on the way.
+
+00:00:19.400 --> 00:00:24.079
+So, why write tests for GNU Hyperbole?
+
+00:00:24.080 --> 00:00:25.679
+There is some background.
+
+00:00:25.680 --> 00:00:27.959
+I'm the co-maintainer of GNU Hyperbole
+
+00:00:27.960 --> 00:00:33.479
+together with Bob Weiner. Bob is the author of the package.
+
+00:00:33.480 --> 00:00:34.680
+The package is available through
+
+00:00:34.681 --> 00:00:38.799
+the Emacs package manager and GNU Elpa
+
+00:00:38.800 --> 00:00:42.599
+if you would want to try it out.
+
+00:00:42.600 --> 00:00:46.359
+The package has some age. I think it dates back to
+
+00:00:46.360 --> 00:00:50.119
+a first release around 1993, which is also
+
+00:00:50.120 --> 00:00:54.799
+when I got in contact with the package the first time.
+
+00:00:54.800 --> 00:00:58.239
+I was a user of the package for many years.
+
+00:00:58.240 --> 00:01:03.119
+Later, I became the maintainer of the package for the FSF.
+
+00:01:03.120 --> 00:01:04.679
+That was although I did not have
+
+00:01:04.680 --> 00:01:09.039
+much knowledge of Emacs Lisp,
+
+00:01:09.040 --> 00:01:12.679
+and I still have a lot to learn.
+
+00:01:12.680 --> 00:01:15.959
+A few years ago, we started to work actively on the package,
+
+00:01:15.960 --> 00:01:20.839
+with setting up goals and having meetings.
+
+00:01:20.840 --> 00:01:24.959
+So my starting point is that I had experience
+
+00:01:24.960 --> 00:01:27.439
+with test automation from development
+
+00:01:27.440 --> 00:01:30.599
+in C++, Java and Python
+
+00:01:30.600 --> 00:01:37.239
+using different x-unit frameworks like cppunit, junit.
+
+00:01:37.240 --> 00:01:40.039
+That was in my daytime work where
+
+00:01:40.040 --> 00:01:41.959
+the technique of using pull requests
+
+00:01:41.960 --> 00:01:46.719
+with changes backed up by tests were the daily routine.
+
+00:01:46.720 --> 00:01:49.199
+It was really a requirement for a change to go in
+
+00:01:49.200 --> 00:01:52.159
+to have supporting test cases.
+
+00:01:52.160 --> 00:01:58.559
+I believe, a quite common setup and requirement these days.
+
+00:01:58.560 --> 00:02:02.039
+I also had been an Emacs user for many years,
+
+00:02:02.040 --> 00:02:04.279
+but with focus on being a user.
+
+00:02:04.280 --> 00:02:09.839
+So as I mentioned, I have limited Emacs Lisp knowledge.
+
+00:02:09.840 --> 00:02:11.359
+When we decided to start
+
+00:02:11.360 --> 00:02:13.959
+to work actively on Hyperbole again,
+
+00:02:13.960 --> 00:02:15.519
+it was natural for me to look into
+
+00:02:15.520 --> 00:02:18.679
+raising the quality by adding unit tests.
+
+00:02:18.680 --> 00:02:20.679
+This also goes hand in hand
+
+00:02:20.680 --> 00:02:25.239
+with running these regularly as part of a build process.
+
+00:02:25.240 --> 00:02:28.439
+All in all, following the current best practice
+
+00:02:28.440 --> 00:02:31.359
+of software development.
+
+00:02:31.360 --> 00:02:36.479
+But since Hyperbole had no tests at all,
+
+00:02:36.480 --> 00:02:38.719
+it would not be enough just to add tests
+
+00:02:38.720 --> 00:02:41.799
+for new or changed functionality.
+
+00:02:41.800 --> 00:02:44.639
+We wanted to add it even broader; ideally, everywhere.
+
+00:02:44.640 --> 00:02:48.399
+So work started with adding tests here and there
+
+00:02:48.400 --> 00:02:52.039
+based on our gut feeling where it would be most useful.
+
+00:02:52.040 --> 00:02:55.799
+This work is still ongoing.
+
+00:02:55.800 --> 00:02:58.119
+So this is where my journey starts
+
+00:02:58.120 --> 00:03:00.759
+with much functionality to test,
+
+00:03:00.760 --> 00:03:03.359
+no knowledge of what testing frameworks existed,
+
+00:03:03.360 --> 00:03:11.159
+and not really knowing a lot about Emacs Lisp at all.
+
+NOTE ERT: Emacs Lisp Regression Testing
+
+00:03:11.160 --> 00:03:13.799
+Luckily there is a package for writing tests in Emacs.
+
+00:03:13.800 --> 00:03:17.919
+It is called ERT: Emacs Lisp Regression Testing.
+
+00:03:17.920 --> 00:03:20.959
+It contains both support for defining tests and running them.
+
+00:03:20.960 --> 00:03:24.639
+Defining a test is done with the macro `ert-deftest`.
+
+00:03:24.640 --> 00:03:28.919
+In its simplest form, a test has a name, a doc string, and a body.
+
+00:03:28.920 --> 00:03:31.439
+The doc string is where you typically can give
+
+00:03:31.440 --> 00:03:33.799
+a detailed description of the test
+
+00:03:33.800 --> 00:03:35.559
+and has space for more info
+
+00:03:35.560 --> 00:03:42.279
+than what can be given in the test name.
+
+00:03:42.280 --> 00:03:45.239
+The body is where all the interesting things happen.
+
+00:03:45.240 --> 00:03:51.959
+It is here you prepare the test, run it and verify the outcome.
+
+00:03:51.960 --> 00:03:54.239
+Schematically, it looks like this.
+
+00:03:54.240 --> 00:04:00.239
+You have the ert-deftest, you have the test name,
+
+00:04:00.240 --> 00:04:02.799
+and the doc string, and then the body.
+
+00:04:02.800 --> 00:04:06.559
+It is in the body where everything interesting happens.
+
+00:04:06.560 --> 00:04:09.759
+The test is prepared, the function of the test is executed,
+
+00:04:09.760 --> 00:04:13.119
+and the outcome of the test is evaluated.
+
+00:04:13.120 --> 00:04:14.359
+Did the test succeed or not?
+
+NOTE Assertions with `should`
+
+00:04:14.360 --> 00:04:18.479
+The verification of a test is performed with
+
+00:04:18.480 --> 00:04:21.479
+one or more so-called assertions.
+
+00:04:21.480 --> 00:04:24.999
+In ERT, they are implemented
+
+00:04:25.000 --> 00:04:26.599
+with the macro `should`
+
+00:04:26.600 --> 00:04:33.559
+together with a set of related macros.
+
+00:04:33.560 --> 00:04:35.519
+`should` takes a form as argument,
+
+00:04:35.520 --> 00:04:37.839
+and if the form evaluates to nil,
+
+00:04:37.840 --> 00:04:48.580
+the test has failed. So let's look at an example.
+
+00:04:48.581 --> 00:04:51.919
+This simple test verifies that the function `+`
+
+00:04:51.920 --> 00:04:56.919
+can add the numbers 2 and 3 and get the result 5.
+
+NOTE Running a test case
+
+00:04:56.920 --> 00:05:01.959
+So now we have defined a test case. How do we run it?
+
+00:05:01.960 --> 00:05:03.919
+The ERT package has the function (or
+
+00:05:03.920 --> 00:05:09.519
+rather convenience alias) `ert`. It takes a test selector.
+
+00:05:09.520 --> 00:05:19.759
+The test name works as a selector for running just one test.
+
+00:05:19.760 --> 00:05:27.900
+So here we have the example. Let's evaluate it.
+
+00:05:27.901 --> 00:05:34.519
+We define it and then we run it using ERT.
+
+00:05:34.520 --> 00:05:42.399
+As you see, we get prompted for a test selector
+
+00:05:42.400 --> 00:05:46.319
+but we only have one test case defined at the moment.
+
+00:05:46.320 --> 00:05:55.919
+It's the example 0. So let's hit RET.
+
+00:05:55.920 --> 00:05:58.959
+As you see here, we get some output
+
+00:05:58.960 --> 00:06:01.359
+describing what we have just done.
+
+00:06:01.360 --> 00:06:04.839
+There is one test case it has passed, zero failed,
+
+00:06:04.840 --> 00:06:07.839
+zero skipped, total 1 of 1 test case
+
+00:06:07.840 --> 00:06:14.439
+and some time stamps for the execution.
+
+00:06:14.440 --> 00:06:18.519
+We also see this green mark here indicating one test case
+
+00:06:18.520 --> 00:06:23.039
+and that it was successful.
+
+00:06:23.040 --> 00:06:29.659
+For inspecting the test, we can hit the letter `l`
+
+00:06:29.660 --> 00:06:32.839
+which shows all the `should` forms
+
+00:06:32.840 --> 00:06:37.779
+that was executed during this test case.
+
+00:06:37.780 --> 00:06:39.919
+So here we see that we have the `should`,
+
+00:06:39.920 --> 00:06:47.999
+one `should` executed, and we see the form equals to 2,
+
+00:06:48.000 --> 00:06:49.799
+and it was 5 equals to 5.
+
+00:06:49.800 --> 00:06:54.559
+So a good example of a successful test case.
+
+NOTE Debug a test
+
+00:06:54.560 --> 00:06:57.919
+So now we've seen how we can run a test case.
+
+00:06:57.920 --> 00:07:03.799
+Can we debug it? Yes. For debugging a test case,
+
+00:07:03.800 --> 00:07:07.939
+the `ert-deftest` can be set up using `edebug-defun`,
+
+00:07:07.940 --> 00:07:10.319
+just as a function or macro is set up
+
+00:07:10.320 --> 00:07:18.819
+or instrumented for debugging. So let's try that.
+
+00:07:18.820 --> 00:07:24.119
+So we try `edebug-defun` here.
+
+00:07:24.120 --> 00:07:28.279
+Now it's instrumented for debugging.
+
+00:07:28.280 --> 00:07:35.659
+And we run it, `ert`, and we're inside the debugger,
+
+00:07:35.660 --> 00:07:40.679
+and we can inspect here what's happening.
+
+00:07:40.680 --> 00:07:46.960
+Step through it and yes it succeeded just as before.
+
+NOTE Commercial break: Hyperbole
+
+00:07:50.380 --> 00:07:56.879
+It's time for a commercial break!
+
+00:07:56.880 --> 00:08:00.079
+Hyperbole itself can help with running tests
+
+00:08:00.080 --> 00:08:03.639
+and also help with running them in debug mode.
+
+00:08:03.640 --> 00:08:08.519
+That is because hyperbole identifies the `ert-deftest`
+
+00:08:08.520 --> 00:08:12.679
+as an implicit button. An implicit button is basically
+
+00:08:12.680 --> 00:08:13.759
+a string or pattern
+
+00:08:13.760 --> 00:08:16.799
+that Hyperbole has assigned some meaning to.
+
+00:08:16.800 --> 00:08:19.959
+For the string `ert-deftest`, it is to run the test case.
+
+00:08:19.960 --> 00:08:24.559
+You activate the button with the action-key.
+
+00:08:24.560 --> 00:08:27.079
+The standard binding is the middle mouse button,
+
+00:08:27.080 --> 00:08:33.040
+or from the keyboard, M-RET.
+
+00:08:33.041 --> 00:08:34.799
+So let's try that.
+
+00:08:34.800 --> 00:08:42.219
+We move the cursor here and then we type M-RET.
+
+00:08:42.220 --> 00:08:47.959
+And boom, the test case was executed.
+
+00:08:47.960 --> 00:08:54.479
+And to run it in debug mode we type C-u M-RET
+
+00:08:54.480 --> 00:08:57.719
+to get the assist key, and then we're in the debugger.
+
+00:08:57.720 --> 00:09:10.479
+So that's pretty useful and convenient.
+
+NOTE Instrument function on the fly
+
+00:09:10.480 --> 00:09:13.719
+A related useful feature here is the step-in functionality
+
+00:09:13.720 --> 00:09:16.399
+bound to the letter i in `debug-mode`.
+
+00:09:16.400 --> 00:09:18.119
+It allows you to step into a function
+
+00:09:18.120 --> 00:09:20.479
+and continue debugging from there.
+
+00:09:20.480 --> 00:09:22.839
+For the cases where your test does not do what you want,
+
+00:09:22.840 --> 00:09:25.119
+looking at what happens in the function of the test
+
+00:09:25.120 --> 00:09:37.259
+can be really useful. Let's try that with another example.
+
+00:09:37.260 --> 00:09:43.359
+So here we have two helper functions, one `f1-add`,
+
+00:09:43.360 --> 00:09:47.439
+that use the built-in `+` function
+
+00:09:47.440 --> 00:09:52.239
+and then we have `my-add` that uses that function.
+
+00:09:52.240 --> 00:09:59.399
+So we're going to test myadd.
+
+00:09:59.400 --> 00:10:02.919
+And then let's run this.
+
+00:10:02.920 --> 00:10:05.959
+Let's run this using hyperbole in debug mode
+
+00:10:05.960 --> 00:10:10.079
+C-u M-RET. We're in the debugger again,
+
+00:10:10.080 --> 00:10:15.639
+and let's step up front to my function under test
+
+00:10:15.640 --> 00:10:19.359
+and then press `i` for getting it instrumented
+
+00:10:19.360 --> 00:10:23.019
+and going into it for debugging.
+
+00:10:23.020 --> 00:10:25.139
+And here we can expect that it's getting
+
+00:10:25.140 --> 00:10:26.559
+the arguments 1 and 3,
+
+00:10:26.560 --> 00:10:30.999
+and it returns the result 4 as expected.
+
+00:10:31.000 --> 00:10:39.119
+And yes, of course, our test case will then succeed.
+
+NOTE Mocking
+
+00:10:39.120 --> 00:10:41.839
+The next tool in our toolbox is mocking.
+
+00:10:41.840 --> 00:10:46.239
+Mocking is needed when we want to simulate the response
+
+00:10:46.240 --> 00:10:49.279
+from a function used by the function under test.
+
+00:10:49.280 --> 00:10:53.139
+That is the implementation of the function.
+
+00:10:53.140 --> 00:10:56.119
+This could be for various reasons.
+
+00:10:56.120 --> 00:11:00.879
+One example could be because it would be hard or impossible
+
+00:11:00.880 --> 00:11:04.199
+in the test setup to get the behavior you want to test for,
+
+00:11:04.200 --> 00:11:06.279
+like an external error case.
+
+00:11:06.280 --> 00:11:08.679
+But the mock can also be used to verify
+
+00:11:08.680 --> 00:11:11.619
+that the function is called with a specific argument.
+
+00:11:11.620 --> 00:11:14.559
+We can view it as a way to isolate the function on the test
+
+00:11:14.560 --> 00:11:16.719
+from its dependencies.
+
+00:11:16.720 --> 00:11:18.959
+So in order to test the function in isolation,
+
+00:11:18.960 --> 00:11:22.079
+we need to cut out any dependencies to external behavior.
+
+00:11:22.080 --> 00:11:25.839
+Most obvious would be dependencies to external resources,
+
+00:11:25.840 --> 00:11:27.639
+such as web pages. As an example:
+
+00:11:27.640 --> 00:11:30.639
+Hyperbole contains functionality to link you to
+
+00:11:30.640 --> 00:11:34.239
+social media resources and other resources on the net.
+
+00:11:34.240 --> 00:11:37.899
+Testing that would require the test system to call out
+
+00:11:37.900 --> 00:11:39.639
+to the social media resources
+
+00:11:39.640 --> 00:11:43.539
+and would depend on it being available, etc.
+
+00:11:43.540 --> 00:11:45.479
+Nothing technically stops a test case
+
+00:11:45.480 --> 00:11:47.239
+to depend on the external resources,
+
+00:11:47.240 --> 00:11:51.319
+but would, if nothing else, be flaky or slow.
+
+00:11:51.320 --> 00:11:53.759
+It could be part of an end-to-end suite
+
+00:11:53.760 --> 00:11:57.179
+where we want to test that it works all the way.
+
+00:11:57.180 --> 00:11:59.719
+In this case, we want to look at the isolated case
+
+00:11:59.720 --> 00:12:04.099
+that can be run with no dependency on external resources.
+
+00:12:04.100 --> 00:12:06.679
+What you want to do is to replace the function with a mock
+
+00:12:06.680 --> 00:12:10.339
+that behaves as the real function would do.
+
+00:12:10.340 --> 00:12:11.639
+The package I have found
+
+00:12:11.640 --> 00:12:14.319
+and have used for mocking is `el-mock`.
+
+00:12:14.320 --> 00:12:21.839
+The workhorse in this package is the `with-mock` macro.
+
+00:12:21.840 --> 00:12:26.519
+It looks like this: `with-mock` followed by a body.
+
+00:12:26.520 --> 00:12:30.439
+In the execution of the body, stubs and mocks
+
+00:12:30.440 --> 00:12:32.899
+defined in the body is respected.
+
+00:12:32.900 --> 00:12:39.199
+Let's look at some examples to make that clearer.
+
+00:12:39.200 --> 00:12:42.079
+In this case, we have the macro `with-mock`.
+
+00:12:42.080 --> 00:12:43.959
+It works so that the expression
+
+00:12:43.960 --> 00:12:48.639
+`stub + => 10` is interpreted
+
+00:12:48.640 --> 00:12:51.919
+so that the function `+` will be replaced with the stub.
+
+00:12:51.920 --> 00:12:56.779
+The stub will return 10 regardless how it is called.
+
+00:12:56.780 --> 00:12:58.119
+Note that the stub function
+
+00:12:58.120 --> 00:13:00.199
+does not have to be called at this level
+
+00:13:00.200 --> 00:13:02.799
+but could be called at any level in the call chain.
+
+00:13:02.800 --> 00:13:07.479
+By knowing how the function under test is implemented
+
+00:13:07.480 --> 00:13:09.319
+and how the implementation works,
+
+00:13:09.320 --> 00:13:11.959
+you can find function calls you want to mock
+
+00:13:11.960 --> 00:13:14.999
+to force certain behavior that you want to test,
+
+00:13:15.000 --> 00:13:18.999
+or to avoid calls to external resources, slow calls, etc.
+
+00:13:19.000 --> 00:13:21.959
+Simply isolate the function under test
+
+00:13:21.960 --> 00:13:26.119
+and simulate its environment.
+
+00:13:26.120 --> 00:13:28.639
+Mock is a little bit more sophisticated
+
+00:13:28.640 --> 00:13:30.079
+and depends on the arguments
+
+00:13:30.080 --> 00:13:31.479
+that the mock function is called with.
+
+00:13:31.480 --> 00:13:33.847
+Or more precise, it is checked
+
+00:13:33.848 --> 00:13:35.519
+after the `with-mock` clause
+
+00:13:35.520 --> 00:13:38.079
+that the arguments match the arguments it was called with
+
+00:13:38.080 --> 00:13:39.759
+or even if it was called at all.
+
+00:13:39.760 --> 00:13:41.839
+If it is called with other arguments
+
+00:13:41.840 --> 00:13:43.719
+there will be an error,
+
+00:13:43.720 --> 00:13:46.479
+and if it's not called, it is also an error.
+
+00:13:46.480 --> 00:13:48.359
+So this way, we are sure that the function
+
+00:13:48.360 --> 00:13:51.319
+we were expected to be called actually was called.
+
+00:13:51.320 --> 00:13:53.399
+An important piece of the testing.
+
+00:13:53.400 --> 00:13:56.239
+So we are sure that the mock we have provided
+
+00:13:56.240 --> 00:14:03.999
+actually is triggered by the test case.
+
+00:14:04.000 --> 00:14:08.159
+So here we have an example of `with-mock`
+
+00:14:08.160 --> 00:14:18.879
+where the `f1-add` function is mocked,
+
+00:14:18.880 --> 00:14:21.999
+so that if it's called with 2 and 3 as arguments,
+
+00:14:22.000 --> 00:14:24.919
+it will return 10. Then we have a test case
+
+00:14:24.920 --> 00:14:27.999
+where we try the `my-add` function,
+
+00:14:28.000 --> 00:14:30.319
+as you might remember, and call that with 2 and 3
+
+00:14:30.320 --> 00:14:32.799
+and see that it should also then return 10
+
+00:14:32.800 --> 00:14:41.239
+because it's using `f1-add`.
+
+NOTE cl-letf
+
+00:14:41.240 --> 00:14:44.559
+Moving over to `cl-letf`.
+
+00:14:44.560 --> 00:14:47.679
+In rare occasions, the limitations of `el-mock` means
+
+00:14:47.680 --> 00:14:50.239
+you would want to implement a full-fledged function
+
+00:14:50.240 --> 00:14:52.979
+to be used under test.
+
+00:14:52.980 --> 00:14:55.439
+Then the macro `cl-letf` can be useful.
+
+00:14:55.440 --> 00:14:57.879
+However, you need to handle the case yourself
+
+00:14:57.880 --> 00:15:00.099
+if the function was not called.
+
+00:15:00.100 --> 00:15:03.519
+Looking through the test cases where I have used `cl-letf`,
+
+00:15:03.520 --> 00:15:06.119
+I think most can be implemented using plain mocking.
+
+00:15:06.120 --> 00:15:11.239
+Cases left is where the args to the mock might be different
+
+00:15:11.240 --> 00:15:13.739
+due to environment issues.
+
+00:15:13.740 --> 00:15:24.099
+In that case, a static mock will not work.
+
+NOTE Hooks
+
+00:15:24.100 --> 00:15:30.719
+Another trick is that functions that uses hooks.
+
+00:15:30.720 --> 00:15:35.639
+You can overload or replace the hooks to do the testing.
+
+00:15:35.640 --> 00:15:40.759
+So you can use the hook function just to do the verification
+
+00:15:40.760 --> 00:15:43.119
+and not do anything useful in the hook.
+
+00:15:43.120 --> 00:15:45.079
+Also, here you need to be careful
+
+00:15:45.080 --> 00:15:55.719
+to make sure the test handler is called and nothing else.
+
+NOTE Side effects and initial buffer state
+
+00:15:55.720 --> 00:15:57.679
+So far we have been talking about testing
+
+00:15:57.680 --> 00:15:59.039
+and what the function returns.
+
+00:15:59.040 --> 00:16:01.119
+In the best of words, we have a pure function
+
+00:16:01.120 --> 00:16:02.959
+that only depends on its arguments
+
+00:16:02.960 --> 00:16:04.939
+and produces no side effects.
+
+00:16:04.940 --> 00:16:06.899
+Many operations produce side effects
+
+00:16:06.900 --> 00:16:09.479
+or operate on the contents of buffers
+
+00:16:09.480 --> 00:16:12.379
+such as writing a message in the message buffer,
+
+00:16:12.380 --> 00:16:15.659
+change the state of a buffer, move point etc.
+
+00:16:15.660 --> 00:16:18.859
+Hyperbole is not an exception. Quite the contrary.
+
+00:16:18.860 --> 00:16:20.839
+Much of the functions creating links
+
+00:16:20.840 --> 00:16:24.420
+are just about updating buffers.
+
+00:16:24.421 --> 00:16:28.559
+This poses a special problem for tests.
+
+00:16:28.560 --> 00:16:29.839
+The test gets longer
+
+00:16:29.840 --> 00:16:31.919
+since you need to create buffers and files,
+
+00:16:31.920 --> 00:16:33.279
+initialize the contents.
+
+00:16:33.280 --> 00:16:35.159
+Verifying the outcome becomes trickier
+
+00:16:35.160 --> 00:16:39.019
+since you need to make sure you look at the right place.
+
+00:16:39.020 --> 00:16:41.039
+At the end of the test, you need to clean up,
+
+00:16:41.040 --> 00:16:43.439
+both for not leaving a lot of garbage
+
+00:16:43.440 --> 00:16:45.279
+in buffers and files around,
+
+00:16:45.280 --> 00:16:48.479
+and even worse, not cause later tests
+
+00:16:48.480 --> 00:16:50.959
+to depend on the leftovers from the other tests.
+
+00:16:50.960 --> 00:16:53.079
+Here are some functions and variables
+
+00:16:53.080 --> 00:17:05.099
+I have found useful for this.
+
+NOTE with-temp-buffer
+
+00:17:05.100 --> 00:17:09.199
+For creating tests: `with-temp-buffer`:
+
+00:17:09.200 --> 00:17:11.919
+it provides you a temp buffer that you visit,
+
+00:17:11.920 --> 00:17:13.719
+and afterwards, there is no need to clean up.
+
+00:17:13.720 --> 00:17:16.519
+This is the first choice if that is all you need.
+
+NOTE make-temp-file
+
+00:17:16.520 --> 00:17:20.519
+`make-temp-file`: If you need a file,
+
+00:17:20.520 --> 00:17:21.959
+this is the function to use.
+
+00:17:21.960 --> 00:17:24.279
+It creates a temp file or a directory.
+
+00:17:24.280 --> 00:17:26.959
+The file can be filled with initial contents.
+
+00:17:26.960 --> 00:17:31.019
+This needs to be cleaned up after a test.
+
+00:17:31.020 --> 00:17:33.287
+Moving on to verifying and debugging:
+
+NOTE buffer-string
+
+00:17:33.288 --> 00:17:38.247
+`buffer-string`: returns the full contents
+
+00:17:38.248 --> 00:17:39.499
+of the buffer as a string.
+
+00:17:39.500 --> 00:17:41.399
+That can sound a bit voluminous,
+
+00:17:41.400 --> 00:17:46.139
+but since tests are normally small, this often works well.
+
+00:17:46.140 --> 00:17:48.439
+I have in particular found good use of comparing
+
+00:17:48.440 --> 00:17:50.399
+the contents of buffers with the empty string.
+
+00:17:50.400 --> 00:17:53.359
+That would give an error, but as we have seen
+
+00:17:53.360 --> 00:17:56.079
+with the output produced by the `should` assertion,
+
+00:17:56.080 --> 00:17:58.079
+this is almost like a print statement
+
+00:17:58.080 --> 00:18:01.199
+and can be compared with the good old technique
+
+00:18:01.200 --> 00:18:04.399
+of debugging with print statements.
+
+00:18:04.400 --> 00:18:06.247
+There might be other ways to do the same
+
+00:18:06.248 --> 00:18:09.919
+as we saw with debugging.
+
+NOTE buffer-name
+
+00:18:09.920 --> 00:18:13.719
+buffer-name: Getting the buffer name is good
+
+00:18:13.720 --> 00:18:16.239
+to verify what buffer we are looking at.
+
+00:18:16.240 --> 00:18:18.359
+I often found it useful to check
+
+00:18:18.360 --> 00:18:21.119
+that my assumptions on what buffer I am acting on
+
+00:18:21.120 --> 00:18:23.399
+is correct by adding `should` clauses
+
+00:18:23.400 --> 00:18:25.399
+in the middle of the test execution
+
+00:18:25.400 --> 00:18:27.399
+or after preparing the test input.
+
+00:18:27.400 --> 00:18:31.679
+Sometimes Emacs can switch buffers in strange ways,
+
+00:18:31.680 --> 00:18:34.199
+maybe because the test case is badly written,
+
+00:18:34.200 --> 00:18:37.239
+and making sure your assumptions are correct
+
+00:18:37.240 --> 00:18:40.339
+is a good sanity check.
+
+00:18:40.340 --> 00:18:42.239
+Even the ert package does
+
+00:18:42.240 --> 00:18:44.879
+some buffer and windows manipulation for its reporting
+
+00:18:44.880 --> 00:18:47.487
+that I have not fully learned how to master,
+
+00:18:47.488 --> 00:18:51.979
+so assertion for checking the sanity of the test is good.
+
+NOTE major-mode
+
+00:18:51.980 --> 00:18:55.679
+Finally, `major-mode`: Verify the buffer has the proper mode.
+
+00:18:55.680 --> 00:19:02.679
+Can also be very useful and is a good sanity check.
+
+NOTE unwind-protect
+
+00:19:02.680 --> 00:19:06.599
+Finally, cleaning up. `unwind-protect`.
+
+00:19:06.600 --> 00:19:09.039
+The tool for cleaning up is the `unwind-protect` form
+
+00:19:09.040 --> 00:19:12.479
+which ensures that the unwind forms
+
+00:19:12.480 --> 00:19:15.439
+always are executed regardless of the outcome of the body.
+
+00:19:15.440 --> 00:19:20.419
+So if your test fails, you are sure the cleanup is executed.
+
+00:19:20.420 --> 00:19:22.759
+Let's look at unwind-protect together with
+
+00:19:22.760 --> 00:19:30.519
+the temporary file example. Many tests look like this.
+
+00:19:30.520 --> 00:19:35.279
+You create some resource, you call `unwind-protect`,
+
+00:19:35.280 --> 00:19:42.759
+you do the test, and then afterwards you do the cleanup.
+
+00:19:42.760 --> 00:19:46.359
+The cleanup for a file and a buffer is so common,
+
+00:19:46.360 --> 00:19:50.999
+so I have created a helper for that.
+
+00:19:51.000 --> 00:19:56.559
+It looks like this.
+
+00:19:56.560 --> 00:19:59.179
+The trick with the `buffer-modified` flag
+
+00:19:59.180 --> 00:20:00.719
+is to avoid getting prompted
+
+00:20:00.720 --> 00:20:03.219
+for killing a buffer that is not saved.
+
+00:20:03.220 --> 00:20:05.439
+The test buffers are often in the state
+
+00:20:05.440 --> 00:20:15.099
+where they have not been saved but modified.
+
+NOTE Input, with-simulated-input
+
+00:20:15.100 --> 00:20:19.679
+Another problem for tests are input.
+
+00:20:19.680 --> 00:20:21.559
+In the middle of execution a function
+
+00:20:21.560 --> 00:20:24.039
+might want to have some interaction with the user.
+
+00:20:24.040 --> 00:20:26.959
+Testing this poses a problem, not only in that
+
+00:20:26.960 --> 00:20:31.199
+the input matters, but also as how even to get the test case
+
+00:20:31.200 --> 00:20:34.079
+to recognize the input!?
+
+00:20:34.080 --> 00:20:36.039
+Ideally the tests are run in batch mode,
+
+00:20:36.040 --> 00:20:38.919
+which in some sense means no user interaction.
+
+00:20:38.920 --> 00:20:42.999
+In batch mode, there is no event loop running.
+
+00:20:43.000 --> 00:20:47.179
+Fortunately, there is a package `with-simulated-input`
+
+00:20:47.180 --> 00:20:53.259
+that gets you around these issues.
+
+00:20:53.260 --> 00:20:55.399
+This is a macro that allows us
+
+00:20:55.400 --> 00:20:56.999
+to define a set of characters
+
+00:20:57.000 --> 00:20:59.079
+that will be read by the function under the test,
+
+00:20:59.080 --> 00:21:02.579
+and all of this works in batch mode. It looks like this.
+
+00:21:02.580 --> 00:21:04.159
+We have `with-simulated-input`,
+
+00:21:04.160 --> 00:21:09.839
+and then a string of characters, and then a body.
+
+00:21:09.840 --> 00:21:11.647
+The form takes a string of keys
+
+00:21:11.648 --> 00:21:13.119
+and runs the rest of the body,
+
+00:21:13.120 --> 00:21:15.439
+and if there are input required,
+
+00:21:15.440 --> 00:21:18.119
+it is picked from the string of keys.
+
+00:21:18.120 --> 00:21:20.421
+In our example, the `read-string` call
+
+00:21:20.422 --> 00:21:21.719
+will read up until RET,
+
+00:21:21.720 --> 00:21:26.119
+and then return the characters read.
+
+00:21:26.120 --> 00:21:29.639
+As you see in the example, space needs to be provided
+
+00:21:29.640 --> 00:21:38.459
+by the string SPC, as return by the string RET.
+
+NOTE Running all tests
+
+00:21:38.460 --> 00:21:40.799
+So now we have seen ways to create test cases
+
+00:21:40.800 --> 00:21:43.219
+and even make it possible to run some of them
+
+00:21:43.220 --> 00:21:44.679
+that has I/O in batch mode.
+
+00:21:44.680 --> 00:21:47.279
+But the initial goal was to run them all at once.
+
+00:21:47.280 --> 00:21:48.919
+How do you do that?
+
+00:21:48.920 --> 00:21:51.759
+Let's go back to the `ert` command.
+
+00:21:51.760 --> 00:21:53.799
+It prompts for a test selector.
+
+00:21:53.800 --> 00:21:56.279
+If we give it the selector `t`,
+
+00:21:56.280 --> 00:21:59.259
+it will run all tests we have currently defined.
+
+00:21:59.260 --> 00:22:05.779
+Let's try that with the subset of the Hyperbole tests.
+
+00:22:05.780 --> 00:22:09.559
+Here is the test folder in the Hyperbole directory.
+
+00:22:09.560 --> 00:22:18.819
+Let's go up here and load all the demo tests.
+
+00:22:18.820 --> 00:22:21.207
+And then try to run `ert`.
+
+00:22:21.208 --> 00:22:26.119
+Now we see that we have a bunch of test cases.
+
+00:22:26.120 --> 00:22:27.919
+We can all run them individually,
+
+00:22:27.920 --> 00:22:31.719
+but we can run them with `t` instead.
+
+00:22:31.720 --> 00:22:35.459
+We will run them all at once.
+
+00:22:35.460 --> 00:22:51.419
+So now, ert is executing all our test cases.
+
+00:22:51.420 --> 00:22:57.079
+So here we have a nice green display
+
+00:22:57.080 --> 00:23:03.219
+with all the test cases.
+
+NOTE Batch mode
+
+00:23:03.220 --> 00:23:08.159
+So that was fine, but we were still running it manually
+
+00:23:08.160 --> 00:23:11.980
+by calling ert. How could we run it from the command line?
+
+00:23:17.180 --> 00:23:21.499
+Ert comes with functions for running it in batch mode.
+
+00:23:21.500 --> 00:23:25.639
+For Hyperbole, we use `make` for repetitive tasks.
+
+00:23:25.640 --> 00:23:27.119
+So we have a make target
+
+00:23:27.120 --> 00:23:29.279
+that uses the ert batch functionality,
+
+00:23:29.280 --> 00:23:33.259
+and this is the line from the Makefile.
+
+00:23:33.260 --> 00:23:35.479
+This is a bit detailed,
+
+00:23:35.480 --> 00:23:37.539
+but you see that we have a part here
+
+00:23:37.540 --> 00:23:40.779
+where we load the test dependencies.
+
+00:23:40.780 --> 00:23:43.520
+For getting the packages
+
+00:23:43.521 --> 00:23:48.459
+such as `el-mock` and `with-simulated-input` etc. loaded.
+
+00:23:48.460 --> 00:23:53.559
+We also have... I also want to point out here the call to
+
+00:23:53.560 --> 00:23:58.159
+or the setting of `auto-save-default` to `nil`
+
+00:23:58.160 --> 00:24:02.439
+to get away with the prompt for excessive backup files
+
+00:24:02.440 --> 00:24:05.059
+that can pile up after running the tests a few times.
+
+NOTE Skipping tests
+
+00:24:05.060 --> 00:24:06.879
+Even with the help of simulated input,
+
+00:24:06.880 --> 00:24:08.919
+not all tests can be run in batch mode.
+
+00:24:08.920 --> 00:24:10.559
+They would simply not work there
+
+00:24:10.560 --> 00:24:12.439
+and have to be run in an interactive Emacs
+
+00:24:12.440 --> 00:24:14.179
+with the running event loop.
+
+00:24:14.180 --> 00:24:17.919
+One trick still to be able to use batch mode for automation
+
+00:24:17.920 --> 00:24:20.319
+is to put the guard at the top of each test case
+
+00:24:20.320 --> 00:24:22.559
+as the first thing to be executed,
+
+00:24:22.560 --> 00:24:25.719
+so that it kicks in before anything else and stops Emacs
+
+00:24:25.720 --> 00:24:27.199
+to try to run the test case.
+
+00:24:27.200 --> 00:24:35.519
+Now, it looks like this: `(skip-unless (not noninteractive))`.
+
+00:24:35.520 --> 00:24:38.639
+So when ert sees that the test should be skipped, it skips it
+
+00:24:38.640 --> 00:24:40.439
+and makes a note of that,
+
+00:24:40.440 --> 00:24:44.579
+so you will see how many tests that have been skipped.
+
+00:24:44.580 --> 00:24:47.559
+Too bad. We have a number of test cases defined,
+
+00:24:47.560 --> 00:24:51.359
+and to run them, we need to run them manually. Well sort of.
+
+00:24:51.360 --> 00:24:53.807
+Not being able to run all tests easily
+
+00:24:53.808 --> 00:24:58.419
+is a bit counterproductive
+
+00:24:58.420 --> 00:25:00.999
+since our goal is to run all tests.
+
+00:25:01.000 --> 00:25:04.719
+There is however no ert function to run tests in batch mode
+
+00:25:04.720 --> 00:25:06.779
+with an interactive Emacs.
+
+00:25:06.780 --> 00:25:08.479
+The closest I have got is either
+
+00:25:08.480 --> 00:25:10.079
+to start the Emacs from the command line
+
+00:25:10.080 --> 00:25:12.439
+calling the ert function as we just have seen,
+
+00:25:12.440 --> 00:25:14.799
+and then killing it manually when done;
+
+00:25:14.800 --> 00:25:19.599
+or add a function to extract the contents of the ERT buffer
+
+00:25:19.600 --> 00:25:24.599
+when done and echo it to standard output.
+
+00:25:24.600 --> 00:25:27.800
+This is how it looks in the Makefile
+
+00:25:27.801 --> 00:25:31.207
+to get the behavior of cutting and paste,
+
+00:25:31.208 --> 00:25:34.580
+getting the ERT output into a file
+
+00:25:34.581 --> 00:25:36.239
+so we can then kill Emacs
+
+00:25:36.240 --> 00:25:44.799
+and spit out the content of the ERT buffer.
+
+00:25:44.800 --> 00:25:47.739
+One final word here is that
+
+00:25:47.740 --> 00:25:54.559
+when you run this in a continuous integration pipeline,
+
+00:25:54.560 --> 00:25:59.399
+you might not have a TTY for getting Emacs to start,
+
+00:25:59.400 --> 00:26:03.200
+and that is then another problem
+
+00:26:03.201 --> 00:26:05.160
+with getting the interactive mode.
+
+NOTE Conclusion
+
+00:26:08.460 --> 00:26:11.120
+We have reached the end of the talk.
+
+00:26:11.121 --> 00:26:14.159
+If you have any new ideas
+
+00:26:14.160 --> 00:26:16.759
+or have some suggestions for improvements,
+
+00:26:16.760 --> 00:26:18.239
+feel free to reach out
+
+00:26:18.240 --> 00:26:21.100
+because I am still on the learning curve of writing,
+
+00:26:21.101 --> 00:26:25.299
+how to write good test cases.
+
+00:26:25.300 --> 00:26:27.639
+If you look at the test cases we have in Hyperbole
+
+00:26:27.640 --> 00:26:29.799
+and you think they might contradict what I am saying here,
+
+00:26:29.800 --> 00:26:32.579
+it is OK. It is probably right.
+
+00:26:32.580 --> 00:26:34.599
+I have changed the style as I go
+
+00:26:34.600 --> 00:26:36.639
+and we have not yet refactored all tests
+
+00:26:36.640 --> 00:26:38.579
+to benefit from new designs.
+
+00:26:38.580 --> 00:26:40.599
+That is also the beauty of the test case.
+
+00:26:40.600 --> 00:26:43.319
+As long as it serves its purpose, it is not terrible
+
+00:26:43.320 --> 00:26:47.799
+if it is not optimal or not having the best style.
+
+00:26:47.800 --> 00:26:55.240
+And yes, thanks for listening. Bye.