Rename "js/tests/units" to "js/tests/unit". (#29503)

js/tests/README.md

@@ -1,6 +1,6 @@
 ## How does Bootstrap's test suite work?
 
-Bootstrap uses [Jasmine](https://jasmine.github.io/). Each plugin has a file dedicated to its tests in `tests/units/<plugin-name>.spec.js`.
+Bootstrap uses [Jasmine](https://jasmine.github.io/). Each plugin has a file dedicated to its tests in `tests/unit/<plugin-name>.spec.js`.
 
 * `visual/` contains "visual" tests which are run interactively in real browsers and require manual verification by humans.
 
@@ -9,7 +9,7 @@ To run the unit test suite via [Karma](https://karma-runner.github.io/) and debu
 
 ## How do I add a new unit test?
 
-1. Locate and open the file dedicated to the plugin which you need to add tests to (`tests/units/<plugin-name>.spec.js`).
+1. Locate and open the file dedicated to the plugin which you need to add tests to (`tests/unit/<plugin-name>.spec.js`).
 2. Review the [Jasmine API Documentation](https://jasmine.github.io/pages/docs_home.html) and use the existing tests as references for how to structure your new tests.
 3. Write the necessary unit test(s) for the new or revised functionality.
 4. Run `npm run js-test` to see the results of your newly-added test(s).

js/tests/karma.conf.js

@@ -58,15 +58,15 @@ const conf = {
   },
   files: [
     'node_modules/hammer-simulator/index.js',
-    { pattern: 'js/tests/units/**/*.spec.js', watched: !browserStack }
+    { pattern: 'js/tests/unit/**/*.spec.js', watched: !browserStack }
   ],
   preprocessors: {
-    'js/tests/units/**/*.spec.js': ['rollup']
+    'js/tests/unit/**/*.spec.js': ['rollup']
   },
   rollupPreprocessor: {
     plugins: [
       istanbul({
-        exclude: ['js/tests/units/**/*.spec.js', 'js/tests/helpers/**/*.js']
+        exclude: ['js/tests/unit/**/*.spec.js', 'js/tests/helpers/**/*.js']
       }),
       babel({
         // Only transpile our source code