Document how to run tests

Makefile

@@ -199,7 +199,7 @@ eslint: node_modules
 	$(ESLINT) spec/ --global converse
 
 .PHONY: check
-check: dev eslint
+check: eslint | dist/converse.js dist/converse.css
 	$(KARMA) start karma.conf.js $(ARGS)
 
 .PHONY: test

docs/source/testing.rst

@@ -1,19 +1,68 @@
 Automated tests
 ===============
 
-Converse uses the `Jasmine <https://jasmine.github.io/>`_ testing framework for
-writing tests.
+Converse uses the `Karma <https://karma-runner.github.io/latest/index.html>`_ test runner and
+`Jasmine <https://jasmine.github.io/>`_ testing library for running tests.
 
-Adding tests for your bugfix or feature
-----------------------------------------
+In addition, we use `ESlint <https://eslint.org/>`_ to run a static analysis (aka
+linting) of the source files and report errors.
 
-Take a look at `tests/index.html <https://github.com/jcbrand/converse.js/blob/master/tests/index.html>`_
-and the `spec files <https://github.com/jcbrand/converse.js/blob/master/spec/>`_
-to see how tests are implemented.
+Whenever a commit is pushed to the Converse Github repo, all ESlint checks and
+Jasmine tests are run on `Travis CI <https://travis-ci.org/github/conversejs/converse.js>`_.
 
 Running tests
 -------------
 
-Check that all tests complete sucessfully.
+You can run ESlint by typing ``make eslint``. Similarly the tests can be run via ``make tests``.
 
-Run ``make check`` in your terminal.
+To run both eslint and the tests, you can use ``make check``.
+
+When running ``make test`` or ``make check``, a browser will automatically
+start up, open a tab at http://localhost:9876 and start running the tests.
+
+You'll see a green bar at the top of the page, and on the right inside it is a ``Debug`` button.
+
+It's often helpful to click that button and run the tests in debug mode. This
+way, you see better error output for failed tests.
+
+Automatically run tests on file changes
+***************************************
+
+To automatically run the tests whenever you make a change to any of the
+Converse source code, you can run ``make watch`` in one terminal, and ``make
+tests`` or ``make check`` in another.
+
+``make watch`` will build development bundles of Converse.js (in
+``dist/converse.js`` and ``dist/converse.css``) and automatically rebuild them
+whenever a source file is modified.
+
+Similarly, Karma will make sure that the tests are re-executed when the
+bundle files are rebuilt.
+
+
+Running individual tests
+************************
+
+Converse has over 400 tests, and it can take a few minutes to run through all of them.
+
+When developing on Converse, it's often preferable to have a more rapid
+turnaround time between editing a file and checking whether the most relevant
+tests have passed.
+
+Jasmine tests are described by `it` functions and the tests names are written to
+be read as plain English sentences that start with the word ``it``.
+
+For example:
+
+.. code-block:: javascript
+
+    it("is rejected if it's an unencapsulated forwarded message",
+
+Tests are grouped by `describe` functions, and contained in spec files inside
+the `spec <https://github.com/jcbrand/converse.js/blob/master/spec/>`_ directory.
+
+To run only a single test, you can replace ``it(`` with ``fit(`` for the particular
+test that you want to run. You can also do this for multiple tests. All of them
+will be run whenever ``make test`` executes.
+
+To run only a group of tests, you can similarly replace ``describe(`` with ``fdescribe``.