Adds code coverage workflow.

.github/workflows/code-coverage.yml

@@ -0,0 +1,34 @@
+on: ['push', 'pull_request']
+
+name: Code Coverage
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+
+    strategy:
+      fail-fast: true
+
+    steps:
+      - uses: actions/checkout@v1
+
+      - name: Use Node.js 16.x
+        uses: actions/setup-node@v1
+        with:
+          node-version: 16.x
+
+      - name: Install
+        run: |
+          npm install
+          npm run build
+
+      - name: Lint & Test
+        run: |
+          npm run lint
+          npm run test
+
+      - name: Coveralls
+        uses: coverallsapp/github-action@master
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}

package.json

@@ -38,13 +38,14 @@
     "types/**/*"
   ],
   "scripts": {
-    "test": "jest --coverage",
     "start": "tsc --watch",
     "build": "npx tsc && npx tsc --project tsconfig.prod.json",
+    "precommit": "npm-run-all dev:types dev:test dev:lint dev:pretty",
+    "dev:types": "tsc --noEmit",
+    "dev:test": "jest --coverage",
+    "dev:lint": "eslint 'src/**/*.{js,ts}' --fix ",
+    "dev:pretty": "prettier 'src/**/*.{js,ts}' --write",
     "bench": "npm-run-all build bench:working bench:compare",
-    "lint": "eslint 'src/**/*.{js,ts}' --fix ",
-    "pretty": "prettier 'src/**/*.{js,ts}' --write",
-    "precommit": "npm-run-all build test lint pretty",
     "bench:working": "node benchmarks > \"coverage/working\"",
     "bench:master": "node benchmarks > \"coverage/master\"",
     "bench:compare": "nanobench-compare \"coverage/working\" \"coverage/master\"",

src/utils.ts

@@ -2,7 +2,6 @@
 import type {
   ComponentClass,
   ContextClass,
-  Entity,
   EntityClass,
   SystemClass
 } from './ecs';