Add some docs on how to run the atoms tests

Author: shs96c

javascript/atoms/README.md

@@ -0,0 +1,43 @@
+# Javascript Atoms
+
+These "atoms" provide reusable building blocks for browser automation
+(which is why we call them "atoms"!) They're currently built with the
+Google Closure Compiler, but at some point, we'd love to migrate them
+to TypeScript since Closure isn't as widely known.
+
+## Testing the Atoms
+
+### Iteratively
+
+While working on the atoms, it can be helpful to be able to iterate on
+the code in your IDE of choice, and then run the tests in a
+browser. You can do this by starting a debug server:
+
+```shell
+bazel run javascript/atoms:test_debug_server  
+```
+
+And then navigating to: http://localhost:2310/filez/selenium/javascript/atoms/
+
+You'll be able to browse around the filesystem until you find the test
+you want to work on.
+
+These files are symlinked by bazel to the ones in the source code, so
+edits you make there will be reflected in the code in the browser,
+however, new files and removed files may cause you to need to restart
+the `bazel run` command.
+
+### Using Bazel
+
+You can run all the tests for a browser using:
+
+```shell
+bazel test //javascript/atoms:test{,-chrome,-edge,-safari}
+```
+
+You can also filter to a specific test using the name of the file
+stripped of it's `.html` suffix. For example:
+
+```shell
+bazel test --test_filter=shown_test --//common:headless=false javascript/atoms:test-chrome 
+```