[jest] update config files to get coverage per plugin (#111299) (#111674)

* [jest] update config files to get coverage per plugin

* [docs] add details about plugin coverage collection

* fix path for newsfeed jest config

* fix lint error

* update documentation

* fix lint errors again

* update doc

* fix another lint error

* Update src/plugins/telemetry_management_section/jest.config.js

Co-authored-by: Luke Elmers <[email protected]>

* Update src/plugins/telemetry_management_section/jest.config.js

Co-authored-by: Luke Elmers <[email protected]>

* [kibana_legacy] fix path

Co-authored-by: Luke Elmers <[email protected]>
Co-authored-by: Kibana Machine <[email protected]>
# Conflicts:
#	packages/kbn-ui-framework/README.md
#	src/plugins/legacy_export/jest.config.js

Author: 3 people

dev_docs/key_concepts/anatomy_of_a_plugin.mdx

@@ -32,6 +32,7 @@ plugins/
       plugin.ts
     common
       index.ts
+    jest.config.js
 ```
 
 ### kibana.json
@@ -209,6 +210,29 @@ considerations related to how plugins integrate with core APIs and APIs exposed
 
 `common/index.ts` is the entry-point into code that can be used both server-side or client side.
 
+### jest.config.js
+
+If you are adding unit tests (which we recommend), you will need to add a `jest.config.js` file. Here is an example file that you would use if adding a plugin into the `examples` directory.
+
+```js
+module.exports = {
+  // Default Jest settings, defined in kbn-test package
+  preset: '@kbn/test',
+  // The root of the directory containing package.json
+  rootDir: '../../..',
+  // The directory which Jest should use to search for files in
+  roots: ['<rootDir>/src/plugins/demo'],
+  // The directory where Jest should output plugin coverage details, e.g. html report
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/demo',
+  // A list of reporter names that Jest uses when writing coverage reports, default: ["json"]
+  // "text" is available in console and is good for quick check
+  // "html" helps to dig into specific files and fix coverage
+  coverageReporters: ['text', 'html'],
+  // An array of regexp pattern strings that matched files to include/exclude for code coverage
+  collectCoverageFrom: ['<rootDir>/src/plugins/demo/{common,public,server}/**/*.{ts,tsx}'],
+};
+```
+
 ## How plugin's interact with each other, and Core
 
 The lifecycle-specific contracts exposed by core services are always passed as the first argument to the equivalent lifecycle function in a plugin.

dev_docs/tutorials/testing_plugins.mdx

@@ -928,6 +928,17 @@ describe('Case migrations v7.7.0 -> v7.8.0', () => {
 });
 ```
 
+You can generate code coverage report for a single plugin.
+
+```bash
+yarn jest --coverage --config src/plugins/console/jest.config.js
+```
+
+Html report should be available in `target/kibana-coverage/jest/src/plugins/console` path
+
+We run code coverage daily on CI and ["Kibana Stats cluster"](https://kibana-stats.elastic.dev/s/code-coverage/app/home)
+can be used to view statistics. The report combines code coverage for all jest tests within Kibana repository.
+
 #### Integration testing
 With more complicated migrations, the behavior of the migration may be dependent on values from other plugins which may
 be difficult or even impossible to test with unit tests. You need to actually bootstrap Kibana, load the plugins, and

docs/developer/contributing/development-tests.asciidoc

@@ -56,6 +56,14 @@ kibana/src/plugins/dashboard/server$ yarn test:jest --coverage
 yarn jest --coverage --verbose --config /home/tyler/elastic/kibana/src/plugins/dashboard/jest.config.js server
 ----
 
+You can generate code coverage report for a single plugin.
+
+[source,bash]
+----
+yarn jest --coverage --config src/plugins/console/jest.config.js
+----
+
+Html report is available in target/kibana-coverage/jest/path/to/plugin
 
 [discrete]
 === Running browser automation tests

packages/kbn-ui-framework/README.md

@@ -19,6 +19,9 @@ You can run `node scripts/jest --watch` to watch for changes and run the tests a
 You can run `node scripts/jest --coverage` to generate a code coverage report to see how
 fully-tested the code is.
 
+You can run `node scripts/jest --config path/to/plugin/jest.config.js --coverage` to generate
+a code coverage report for a single plugin.
+
 See the documentation in [`scripts/jest.js`](../scripts/jest.js) for more options.
 
 ## Creating components

src/plugins/advanced_settings/jest.config.js

@@ -10,4 +10,7 @@ module.exports = {
   preset: '@kbn/test',
   rootDir: '../../..',
   roots: ['<rootDir>/src/plugins/advanced_settings'],
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/advanced_settings',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: ['<rootDir>/src/plugins/advanced_settings/{public,server}/**/*.{ts,tsx}'],
 };

src/plugins/bfetch/jest.config.js

@@ -10,4 +10,7 @@ module.exports = {
   preset: '@kbn/test',
   rootDir: '../../..',
   roots: ['<rootDir>/src/plugins/bfetch'],
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/bfetch',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: ['<rootDir>/src/plugins/bfetch/{common,public,server}/**/*.{ts,tsx}'],
 };

src/plugins/chart_expressions/expression_tagcloud/jest.config.js

@@ -10,4 +10,10 @@ module.exports = {
   preset: '@kbn/test',
   rootDir: '../../../../',
   roots: ['<rootDir>/src/plugins/chart_expressions/expression_tagcloud'],
+  coverageDirectory:
+    '<rootDir>/target/kibana-coverage/jest/src/plugins/chart_expressions/expression_tagcloud',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: [
+    '<rootDir>/src/plugins/chart_expressions/expression_tagcloud/{common,public,server}/**/*.{ts,tsx}',
+  ],
 };

src/plugins/charts/jest.config.js

@@ -10,4 +10,7 @@ module.exports = {
   preset: '@kbn/test',
   rootDir: '../../..',
   roots: ['<rootDir>/src/plugins/charts'],
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/charts',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: ['<rootDir>/src/plugins/charts/{common,public,server}/**/*.{ts,tsx}'],
 };

src/plugins/console/jest.config.js

@@ -11,4 +11,7 @@ module.exports = {
   rootDir: '../../..',
   roots: ['<rootDir>/src/plugins/console'],
   testRunner: 'jasmine2',
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/console',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: ['<rootDir>/src/plugins/console/{common,public,server}/**/*.{js,ts,tsx}'],
 };

src/plugins/dashboard/jest.config.js

@@ -11,4 +11,7 @@ module.exports = {
   rootDir: '../../..',
   roots: ['<rootDir>/src/plugins/dashboard'],
   testRunner: 'jasmine2',
+  coverageDirectory: '<rootDir>/target/kibana-coverage/jest/src/plugins/dashboard',
+  coverageReporters: ['text', 'html'],
+  collectCoverageFrom: ['<rootDir>/src/plugins/dashboard/{common,public,server}/**/*.{ts,tsx}'],
 };