Docs: Test examples report errors

.github/workflows/ci.yml

@@ -39,5 +39,10 @@ jobs:
       run: npm install
       env:
         CI: true
+    - name: Install examples/react Packages
+      working-directory: ./examples/react
+      run: npm install
+      env:
+        CI: true
     - name: Test
       run: npm run test-cov

package.json

@@ -22,7 +22,7 @@
   "scripts": {
     "lint": "eslint --ext js,md .",
     "test": "npm run lint && npm run test-cov",
-    "test-cov": "nyc _mocha -- -c tests/lib/**/*.js",
+    "test-cov": "nyc _mocha -- -c tests/{examples,lib}/**/*.js",
     "generate-release": "eslint-generate-release",
     "generate-alpharelease": "eslint-generate-prerelease alpha",
     "generate-betarelease": "eslint-generate-prerelease beta",

tests/examples/all.js

@@ -0,0 +1,41 @@
+"use strict";
+
+const assert = require("chai").assert;
+const execSync = require("child_process").execSync;
+const fs = require("fs");
+const path = require("path");
+const semver = require("semver");
+
+const examples = path.resolve(__dirname, "../../examples/");
+for (const example of fs.readdirSync(examples)) {
+    const cwd = path.join(examples, example);
+
+    // The plugin officially supports ESLint as early as v6, but the examples
+    // use ESLint v7, which has a higher minimum Node.js version than does v6.
+    // Only exercise the example if the running Node.js version satisfies the
+    // minimum version constraint. In CI, this will skip these tests in Node.js
+    // v8 and run them on all other Node.js versions.
+    const eslintPackageJsonPath = require.resolve("eslint/package.json", {
+        paths: [cwd]
+    });
+    const eslintPackageJson = require(eslintPackageJsonPath);
+    if (semver.satisfies(process.version, eslintPackageJson.engines.node)) {
+        describe("examples", () => {
+            describe(example, () => {
+                it("reports errors on code blocks in .md files", () => {
+                    try {
+                        execSync("npx eslint . --format json", { cwd });
+                        assert.fail("ESLint should have found issues.");
+                    } catch (error) {
+                        const results = JSON.parse(error.stdout.toString());
+                        const readme = results.find(result =>
+                            path.basename(result.filePath) == "README.md"
+                        );
+                        assert.isNotNull(readme);
+                        assert.isAbove(readme.messages.length, 0);
+                    }
+                });
+            });
+        });
+    }
+}