chore(changelog): add commit-msg hook to verify commit messages

This adds a Git commit-msg hook which runs after a commit message is
written. It verifies that is matches a certain spec as defined by the
AngularJS document here:
https://docs.google.com/document/d/1QrDFcIiPjSLDn3EL15IJygNPiHORgU1_OOAqWjiDU5Y/edit#
This will allow for autmoated generation of Changelog.md in the future.

Migration notes: Please run `ln -sf ../../validate-commit-msg.js
.git/hooks/commit-msg` to install the commit hook.

validate-commit-msg.spec.js

@@ -0,0 +1,77 @@
+describe('validate-commit-msg.js', function() {
+  var m = require('./validate-commit-msg');
+  var errors = [];
+  var logs = [];
+
+  var VALID = true;
+  var INVALID = false;
+
+  beforeEach(function() {
+    errors.length = 0;
+    logs.length = 0;
+
+    spyOn(console, 'error').andCallFake(function(msg) {
+      errors.push(msg.replace(/\x1B\[\d+m/g, '')); // uncolor
+    });
+
+    spyOn(console, 'log').andCallFake(function(msg) {
+      logs.push(msg.replace(/\x1B\[\d+m/g, '')); // uncolor
+    });
+  });
+
+  describe('validateMessage', function() {
+
+    it('should be valid', function() {
+      expect(m.validateMessage('fixup! fix($compile): something')).toBe(VALID);
+      expect(m.validateMessage('fix($compile): something')).toBe(VALID);
+      expect(m.validateMessage('feat($location): something')).toBe(VALID);
+      expect(m.validateMessage('docs($filter): something')).toBe(VALID);
+      expect(m.validateMessage('style($http): something')).toBe(VALID);
+      expect(m.validateMessage('refactor($httpBackend): something')).toBe(VALID);
+      expect(m.validateMessage('test($resource): something')).toBe(VALID);
+      expect(m.validateMessage('chore($controller): something')).toBe(VALID);
+      expect(m.validateMessage('chore(foo-bar): something')).toBe(VALID);
+      expect(m.validateMessage('chore(*): something')).toBe(VALID);
+      expect(m.validateMessage('chore(guide/location): something')).toBe(VALID);
+      expect(m.validateMessage('revert(foo): something')).toBe(VALID);
+      expect(errors).toEqual([]);
+    });
+
+
+    it('should validate 100 characters length', function() {
+      var msg = "fix($compile): something super mega extra giga tera long, maybe even longer and longer and longer... ";
+
+      expect(m.validateMessage(msg)).toBe(INVALID);
+      expect(errors).toEqual(['INVALID COMMIT MSG: is longer than 100 characters !']);
+    });
+
+
+    it('should validate "<type>(<scope>): <subject>" format', function() {
+      var msg = 'not correct format';
+
+      expect(m.validateMessage(msg)).toBe(INVALID);
+      expect(errors).toEqual(['INVALID COMMIT MSG: does not match "<type>(<scope>): <subject>" ! was: not correct format']);
+    });
+
+
+    it('should validate type', function() {
+      expect(m.validateMessage('weird($filter): something')).toBe(INVALID);
+      expect(errors).toEqual(['INVALID COMMIT MSG: "weird" is not allowed type !']);
+    });
+
+
+    it('should allow empty scope', function() {
+      expect(m.validateMessage('fix: blablabla')).toBe(VALID);
+    });
+
+
+    it('should allow dot in scope', function() {
+      expect(m.validateMessage('chore(mocks.$httpBackend): something')).toBe(VALID);
+    });
+
+
+    it('should ignore msg prefixed with "WIP: "', function() {
+      expect(m.validateMessage('WIP: bullshit')).toBe(VALID);
+    });
+  });
+});