test: add a testing example using jest

.github/workflows/main.yml

@@ -35,16 +35,16 @@ jobs:
         restore-keys: |
           ${{ runner.os }}-yarn-
 
-    - name: Mount bazel cache
-      uses: actions/cache@v1
-      with:
-        path: "/home/runner/.cache/bazel"
-        key: bazel
+    # - name: Mount bazel cache
+    #   uses: actions/cache@v1
+    #   with:
+    #     path: "/home/runner/.cache/bazel"
+    #     key: bazel
 
     - run: yarn
 
     - run: yarn run build
 
-    # - run: yarn run test
+    - run: yarn run test
 
     - run: yarn run shutdown

BUILD.bazel

@@ -1,6 +1,7 @@
 exports_files(
     [
-        "tsconfig.json"
+        "tsconfig.json",
+        "jest.config.js",
     ],
     visibility = ["//visibility:public"],
 )

jest.config.js

@@ -0,0 +1,5 @@
+module.exports = {
+    testEnvironment: 'node',
+    testPathIgnorePatterns: ['/node_modules/'],
+    reporters: ['default']
+}

libs/javascript/jest_test/BUILD.bazel

@@ -0,0 +1,40 @@
+load("@build_bazel_rules_nodejs//:index.bzl", "pkg_npm")
+load("//rules:jest.bzl", "jest_test")
+
+filegroup(
+    name = 'src',
+    srcs = [
+        'index.js',
+    ],
+)
+
+filegroup(
+    name = 'test_src',
+    srcs = [':src'] + glob(['__tests__/**/*.test.js']),
+)
+
+pkg_npm(
+    name = 'pkg',
+    srcs = [
+        'package.json',
+    ],
+    deps = [
+        ':src'
+    ],
+    visibility = ['//visibility:public'],
+)
+
+jest_test(
+    name = 'test',
+    srcs = [":test_src"],
+    jest_config = "//:jest.config.js",
+    tags = [
+        # Need to set the pwd to avoid jest needing a runfiles helper
+        # Windows users with permissions can use --enable_runfiles
+        # to make this test work
+        "no-bazelci-windows",
+    ],
+    deps = [
+        "@npm//:node_modules"
+    ],
+)

libs/javascript/jest_test/__tests__/index.test.js

@@ -0,0 +1,7 @@
+const index = require('../index.js')
+
+describe('example jest test', () => {
+    test('can execute code', () => {
+        expect(index()).toEqual('Hello world')
+    })
+})

libs/javascript/jest_test/index.js

@@ -0,0 +1 @@
+module.exports = () => 'Hello world'

libs/javascript/jest_test/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "lib-javascript-jest-test",
+  "version": "1.0.0",
+  "description": "Javascript package with a jest test",
+  "main": "index.js",
+  "author": "",
+  "license": "MIT"
+}

package.json

@@ -10,13 +10,15 @@
     "@bazel/rollup": "1.5.0",
     "@bazel/typescript": "1.5.0",
     "@types/node": "^12.11.1",
+    "jest": "^25.2.4",
     "rollup": "^1.25.2",
     "typescript": "^3.8.0"
   },
   "scripts": {
     "build": "bazelisk build //...",
     "test": "bazelisk test //...",
     "clean": "bazelisk clean",
-    "shutdown": "bazelisk shutdown"
+    "shutdown": "bazelisk shutdown",
+    "sync": "bazelisk sync"
   }
 }

rules/jest.bzl

@@ -0,0 +1,20 @@
+load("@npm//jest-cli:index.bzl", _jest_test = "jest_test")
+
+def jest_test(name, srcs, deps, jest_config, **kwargs):
+    """A macro around the autogenerated jest_test rule"""
+    args = [
+        "--no-cache",
+        "--no-watchman",
+        "--ci",
+    ]
+    args.extend(["--config", "$(location %s)" % jest_config])
+
+    for src in srcs:
+        args.extend(["--runTestsByPath", "$(locations %s)" % src])
+
+    _jest_test(
+        name = name,
+        data = [jest_config] + srcs + deps,
+        args = args,
+        **kwargs
+    )