ref(dev): Centralize jest config (#4907)

Currently, we configure jest using a mix of `package.json` entries and `jest.config.js` files, and there's a great deal of repetition between configs. To make things DRYer and easier to update (as will happen in future PRs), this aims to fix that by creating a centralized jest config from which all others can inherit. To facilitate this inheritance, all config has been removed from `package.json` files and moved into `jest.config.js` files. 

This change was done in a few distinct stages:

- Extracting the config which was identical across many packages into a central config file, and fixing a mistake they all contained, namely that they were using the regular tsconfig file rather than the test-specific one.
- In the packages which were using exactly that config, creating a new `jest.config.js` file and inheriting directly from the central jest config with no changes.
- In the packages whose config varied only slightly from the boilerplate config, creating a new `jest.config.js` file and inheriting from the central file with small changes. This also required adding `.tsx` files to the central config.
- In the browser package, moving the existing `jest.config.js` for the unit tests to the repo root level and refactoring it to inherit from the central file. This also required specifying a coverage directory in the central config and modifying the browser package's yarn test commands.
- In the node integration test package, refactoring the existing `jest.config.js` to inherit from the central file. This also required creating a test-specific tsconfig to match the one in other packages.
- Finally, making a small optimization (narrowing the scope of where to look for tests) in the now universally-used central config.

Author: lobsterkatie

jest.config.js

@@ -0,0 +1,19 @@
+module.exports = {
+  rootDir: process.cwd(),
+  collectCoverage: true,
+  transform: {
+    '^.+\\.ts$': 'ts-jest',
+    '^.+\\.tsx$': 'ts-jest',
+  },
+  coverageDirectory: '<rootDir>/coverage',
+  moduleFileExtensions: ['js', 'ts', 'tsx'],
+  testEnvironment: 'node',
+  testMatch: ['<rootDir>/**/*.test.ts', '<rootDir>/**/*.test.tsx'],
+  globals: {
+    'ts-jest': {
+      tsconfig: '<rootDir>/tsconfig.test.json',
+      diagnostics: false,
+    },
+  },
+  testPathIgnorePatterns: ['<rootDir>/build/', '<rootDir>/node_modules/'],
+};

packages/browser/jest.config.js

@@ -0,0 +1,7 @@
+const baseConfig = require('../../jest.config.js');
+
+module.exports = {
+  ...baseConfig,
+  testEnvironment: 'jsdom',
+  testMatch: ['<rootDir>/test/unit/**/*.test.ts'],
+};

packages/browser/package.json

@@ -72,11 +72,11 @@
     "size:check:es5": "cat build/bundles/bundle.min.js | gzip -9 | wc -c | awk '{$1=$1/1024; print \"ES5: \",$1,\"kB\";}'",
     "size:check:es6": "cat build/bundles/bundle.es6.min.js | gzip -9 | wc -c | awk '{$1=$1/1024; print \"ES6: \",$1,\"kB\";}'",
     "test": "run-s test:unit",
-    "test:unit": "jest --config test/unit/jest.config.js",
+    "test:unit": "jest",
     "test:integration": "test/integration/run.js",
     "test:integration:checkbrowsers": "node scripts/checkbrowsers.js",
     "test:package": "node test/package/npm-build.js && rm test/package/tmp.js",
-    "test:unit:watch": "jest --config test/unit/jest.config.js --watch",
+    "test:unit:watch": "jest --watch",
     "test:integration:watch": "test/integration/run.js --watch"
   },
   "volta": {

packages/browser/test/unit/jest.config.js

@@ -0,0 +1 @@
+module.exports = require('../../jest.config.js');

packages/core/jest.config.js

@@ -52,25 +52,5 @@
   "volta": {
     "extends": "../../package.json"
   },
-  "jest": {
-    "collectCoverage": true,
-    "transform": {
-      "^.+\\.ts$": "ts-jest"
-    },
-    "moduleFileExtensions": [
-      "js",
-      "ts"
-    ],
-    "testEnvironment": "node",
-    "testMatch": [
-      "**/*.test.ts"
-    ],
-    "globals": {
-      "ts-jest": {
-        "tsConfig": "./tsconfig.json",
-        "diagnostics": false
-      }
-    }
-  },
   "sideEffects": false
 }

packages/core/package.json

@@ -0,0 +1,7 @@
+const baseConfig = require('../../jest.config.js');
+
+module.exports = {
+  ...baseConfig,
+  setupFiles: ['<rootDir>/test/setEnvVars.ts'],
+  testEnvironment: 'jsdom',
+};

packages/gatsby/jest.config.js

@@ -62,31 +62,5 @@
   "volta": {
     "extends": "../../package.json"
   },
-  "jest": {
-    "collectCoverage": true,
-    "transform": {
-      "^.+\\.ts$": "ts-jest",
-      "^.+\\.tsx$": "ts-jest"
-    },
-    "moduleFileExtensions": [
-      "js",
-      "ts",
-      "tsx"
-    ],
-    "testEnvironment": "jsdom",
-    "testMatch": [
-      "**/*.test.ts",
-      "**/*.test.tsx"
-    ],
-    "globals": {
-      "ts-jest": {
-        "tsConfig": "./tsconfig.json",
-        "diagnostics": false
-      }
-    },
-    "setupFiles": [
-      "<rootDir>/test/setEnvVars.ts"
-    ]
-  },
   "sideEffects": false
 }

packages/gatsby/package.json

@@ -0,0 +1 @@
+module.exports = require('../../jest.config.js');

packages/hub/jest.config.js

@@ -49,25 +49,5 @@
   "volta": {
     "extends": "../../package.json"
   },
-  "jest": {
-    "collectCoverage": true,
-    "transform": {
-      "^.+\\.ts$": "ts-jest"
-    },
-    "moduleFileExtensions": [
-      "js",
-      "ts"
-    ],
-    "testEnvironment": "node",
-    "testMatch": [
-      "**/*.test.ts"
-    ],
-    "globals": {
-      "ts-jest": {
-        "tsConfig": "./tsconfig.json",
-        "diagnostics": false
-      }
-    }
-  },
   "sideEffects": false
 }