fix(lint): re-arrange scripts (#36511)

tools/scripts/lint/index.test.js

@@ -0,0 +1,57 @@
+/* global describe it expect jest beforeEach */
+const path = require('path');
+
+const lint = require('.');
+
+describe('markdown linter', () => {
+  let good = { path: path.join(__dirname, './fixtures/good.md') };
+  let badYML = { path: path.join(__dirname, './fixtures/badYML.md') };
+  let badFencing = { path: path.join(__dirname, './fixtures/badFencing.md') };
+  beforeEach(() => {
+    console.log = jest.fn();
+    // the linter signals that a file failed by setting
+    // exitCode to 1, so it needs (re)setting to 0
+    process.exitCode = 0;
+  });
+  afterEach(() => {
+    process.exitCode = 0;
+  });
+
+  it('should pass `good` markdown', done => {
+    function callback() {
+      expect(process.exitCode).toBe(0);
+      done();
+    }
+    lint(good, callback);
+  });
+
+  it('should fail invalid YML blocks', done => {
+    function callback() {
+      expect(process.exitCode).toBe(1);
+      done();
+    }
+    lint(badYML, callback);
+  });
+
+  it('should fail when code fences are not surrounded by newlines', done => {
+    function callback() {
+      expect(process.exitCode).toBe(1);
+      done();
+    }
+    lint(badFencing, callback);
+  });
+
+  it('should write to the console describing the problem', done => {
+    function callback() {
+      const expected =
+        // eslint-disable-next-line max-len
+        'badYML.md: 19: yaml-linter YAML code blocks should be valid [bad indentation of a mapping entry at line 3, column 17:\n          testString: testString\n                    ^] [Context: "```yml"]';
+      expect(console.log.mock.calls.length).toBe(1);
+      expect(console.log.mock.calls[0][0]).toEqual(
+        expect.stringContaining(expected)
+      );
+      done();
+    }
+    lint(badYML, callback);
+  });
+});