[Tests] migrate tests to Github Actions

Author: ljharb

.github/workflows/node-4+.yml

@@ -0,0 +1,72 @@
+name: 'Tests: node.js'
+
+on: [pull_request, push]
+
+jobs:
+  matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      latest: ${{ steps.set-matrix.outputs.requireds }}
+    steps:
+      - uses: ljharb/actions/node/matrix@main
+        id: set-matrix
+        with:
+          versionsAsRoot: true
+          type: 'majors'
+          preset: '>=4'
+
+  latest:
+    needs: [matrix]
+    name: 'latest majors'
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: ${{ fromJson(needs.matrix.outputs.latest) }}
+        eslint:
+          - 7
+          - 6
+          - 5
+          - 4
+          - 3
+        exclude:
+          - node-version: 9
+            eslint: 7
+          - node-version: 8
+            eslint: 7
+          - node-version: 7
+            eslint: 7
+          - node-version: 7
+            eslint: 6
+          - node-version: 6
+            eslint: 7
+          - node-version: 6
+            eslint: 6
+          - node-version: 5
+            eslint: 7
+          - node-version: 5
+            eslint: 6
+          - node-version: 5
+            eslint: 5
+          - node-version: 4
+            eslint: 7
+          - node-version: 4
+            eslint: 6
+          - node-version: 4
+            eslint: 5
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ljharb/actions/node/run@main
+        name: 'npm install && npm run tests-only'
+        with:
+          after_install: npm uninstall --no-save eslint-config-airbnb-base && npm install --no-save "eslint@${{ matrix.eslint }}"
+          node-version: ${{ matrix.node-version }}
+          command: 'test:ci'
+
+  node:
+    name: 'node 4+'
+    needs: [latest]
+    runs-on: ubuntu-latest
+    steps:
+      - run: 'echo tests completed'

.github/workflows/node-pretest.yml

@@ -0,0 +1,37 @@
+name: 'Tests: pretest/posttest'
+
+on: [pull_request, push]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ljharb/actions/node/run@main
+        name: 'npm install && npm run lint'
+        with:
+          node-version: 'lts/*'
+          command: 'lint'
+
+  flow:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ljharb/actions/node/run@main
+        name: 'npm install && npm run flow'
+        with:
+          node-version: 'lts/*'
+          command: 'flow'
+
+  posttest:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ljharb/actions/node/run@main
+        name: 'npm install && npm run posttest'
+        with:
+          node-version: 'lts/*'
+          command: 'posttest'