Add option to forbid empty test suites

docs/index.md

@@ -839,6 +839,7 @@ Rules & Behavior
   --check-leaks              Check for global variable leaks           [boolean]
   --delay                    Delay initial execution of root suite     [boolean]
   --exit                     Force Mocha to quit after tests complete  [boolean]
+  --forbid-empty-suite       Fail if a test suite contains no tests    [boolean]
   --forbid-only              Fail if exclusive test(s) encountered     [boolean]
   --forbid-pending           Fail if pending test(s) encountered       [boolean]
   --global, --globals        List of allowed global variables            [array]
@@ -952,6 +953,12 @@ To ensure your tests aren't leaving messes around, here are some ideas to get st
 - Try something like [wtfnode][npm-wtfnode]
 - Use [`.only`](#exclusive-tests) until you find the test that causes Mocha to hang
 
+### `--forbid-empty-suite`
+
+Enforce a rule that test suites must contain at least one suite, either directly or in an inner suite.
+
+`--forbid-empty-suite` causes Mocha to fail when an empty suite is encountered.
+
 ### `--forbid-only`
 
 Enforce a rule that tests may not be exclusive (use of e.g., `describe.only()` or `it.only()` is disallowed).

lib/cli/run-option-metadata.js

@@ -33,6 +33,7 @@ exports.types = {
     'delay',
     'diff',
     'exit',
+    'forbid-empty-suite',
     'forbid-only',
     'forbid-pending',
     'full-trace',

lib/cli/run.js

@@ -107,6 +107,10 @@ exports.builder = yargs =>
         normalize: true,
         requiresArg: true
       },
+      'forbid-empty-suite': {
+        description: 'Fail if a test suite contains no tests',
+        group: GROUPS.RULES
+      },
       'forbid-only': {
         description: 'Fail if exclusive test(s) encountered',
         group: GROUPS.RULES

lib/mocha.js

@@ -74,6 +74,7 @@ exports.Test = require('./test');
  * @param {boolean} [options.delay] - Delay root suite execution?
  * @param {boolean} [options.diff] - Show diff on failure?
  * @param {string} [options.fgrep] - Test filter given string.
+ * @param {boolean} [options.forbidEmptySuite] - Require at least one test.
  * @param {boolean} [options.forbidOnly] - Tests marked `only` fail the suite?
  * @param {boolean} [options.forbidPending] - Pending tests fail the suite?
  * @param {boolean} [options.fullTrace] - Full stacktrace upon failure?
@@ -121,6 +122,7 @@ function Mocha(options) {
     'color',
     'delay',
     'diff',
+    'forbidEmptySuite',
     'forbidOnly',
     'forbidPending',
     'fullTrace',
@@ -778,6 +780,20 @@ Mocha.prototype.delay = function delay() {
   return this;
 };
 
+/**
+ * Causes running a suite with no tests to fail it.
+ *
+ * @public
+ * @see [CLI option](../#-forbid-empty-suite)
+ * @param {boolean} [forbidEmptySuite=true] - Whether tests marked `only` fail the suite.
+ * @returns {Mocha} this
+ * @chainable
+ */
+Mocha.prototype.forbidEmptySuite = function(forbidEmptySuite) {
+  this.options.forbidEmptySuite = forbidEmptySuite !== false;
+  return this;
+};
+
 /**
  * Causes tests marked `only` to fail the suite.
  *
@@ -855,6 +871,7 @@ Mocha.prototype.run = function(fn) {
   runner.fullStackTrace = options.fullTrace;
   runner.asyncOnly = options.asyncOnly;
   runner.allowUncaught = options.allowUncaught;
+  runner.forbidEmptySuite = options.forbidEmptySuite;
   runner.forbidOnly = options.forbidOnly;
   runner.forbidPending = options.forbidPending;
   if (options.grep) {

lib/runner.js

@@ -713,6 +713,11 @@ Runner.prototype.runSuite = function(suite, fn) {
 
   debug('run suite %s', suite.fullTitle());
 
+  if (this.forbidEmptySuite && suite.isEmpty()) {
+    this.fail(suite, new Error('Empty suite forbidden'));
+    return fn();
+  }
+
   if (!total || (self.failures && suite._bail)) {
     return fn();
   }

lib/suite.js

@@ -201,6 +201,20 @@ Suite.prototype.bail = function(bail) {
   return this;
 };
 
+/**
+ * Check if this suite contains no tests
+ *
+ * @private
+ */
+Suite.prototype.isEmpty = function() {
+  if (this.tests.length > 0) {
+    return false;
+  }
+  return this.suites.every(function(suite) {
+    return suite.isEmpty();
+  });
+};
+
 /**
  * Check if this suite or its parent suite is marked as pending.
  *

test/integration/fixtures/options/forbid-empty-suite/empty-nested-suite.fixture.js

@@ -0,0 +1,8 @@
+'use strict';
+
+describe('parent suite', function() {
+  describe('suite with test', function() {
+    it('it nested', function() {});
+  });
+  describe('empty suite', function() {});
+});

test/integration/fixtures/options/forbid-empty-suite/empty-suite.fixture.js

@@ -0,0 +1,3 @@
+'use strict';
+
+describe('forbid empty suite - empty', function() {});

test/integration/fixtures/options/forbid-empty-suite/empty.fixture.js

@@ -0,0 +1 @@
+'use strict';

test/integration/fixtures/options/forbid-empty-suite/nested-suite.fixture.js

@@ -0,0 +1,7 @@
+'use strict';
+
+describe('parent suite', function() {
+  describe('suite with test', function() {
+    it('it nested', function() {});
+  });
+});

test/integration/fixtures/options/forbid-empty-suite/passed.fixture.js

@@ -0,0 +1,7 @@
+'use strict';
+
+describe('forbid empty suite - not empty', function() {
+  it('test1', function() {});
+  it('test2', function() {});
+  it('test3', function() {});
+});

test/integration/options/forbidEmptySuite.spec.js

@@ -0,0 +1,69 @@
+'use strict';
+
+var path = require('path').posix;
+var helpers = require('../helpers');
+var runMocha = helpers.runMocha;
+var runMochaJSON = helpers.runMochaJSON;
+
+describe('--forbid-empty-suite', function() {
+  var args = [];
+  var emptySuiteErrorMessage = 'Empty suite forbidden';
+
+  before(function() {
+    args = ['--forbid-empty-suite'];
+  });
+
+  it('should succeed if there are tests', function(done) {
+    var fixture = path.join('options', 'forbid-empty-suite', 'passed');
+    runMochaJSON(fixture, args, function(err, res) {
+      if (err) {
+        return done(err);
+      }
+      expect(res, 'to have passed');
+      done();
+    });
+  });
+
+  it('should succeed if there is an inner suite with tests', function(done) {
+    var fixture = path.join('options', 'forbid-empty-suite', 'nested-suite');
+    runMochaJSON(fixture, args, function(err, res) {
+      if (err) {
+        return done(err);
+      }
+      expect(res, 'to have passed');
+      done();
+    });
+  });
+
+  var forbidEmptySuiteFailureTests = {
+    'should fail if there are no test suites': 'empty',
+    'should fail if there are no tests': 'empty-suite',
+    'should fail if there is an inner suite with no tests': 'empty-nested-suite'
+  };
+
+  Object.keys(forbidEmptySuiteFailureTests).forEach(function(title) {
+    it(title, function(done) {
+      var fixture = path.join(
+        'options',
+        'forbid-empty-suite',
+        forbidEmptySuiteFailureTests[title]
+      );
+      var spawnOpts = {stdio: 'pipe'};
+      runMocha(
+        fixture,
+        args,
+        function(err, res) {
+          if (err) {
+            return done(err);
+          }
+          expect(res, 'to satisfy', {
+            code: 1,
+            output: new RegExp(emptySuiteErrorMessage)
+          });
+          done();
+        },
+        spawnOpts
+      );
+    });
+  });
+});

test/unit/mocha.spec.js

@@ -191,6 +191,25 @@ describe('Mocha', function() {
     });
   });
 
+  describe('#forbidEmptySuite()', function() {
+    it('should set the forbidEmptySuite option to true', function() {
+      var mocha = new Mocha(opts);
+      mocha.forbidEmptySuite();
+      expect(mocha.options, 'to have property', 'forbidEmptySuite', true);
+    });
+
+    it('should set the forbidEmptySuite option to false', function() {
+      var mocha = new Mocha(opts);
+      mocha.forbidEmptySuite(false);
+      expect(mocha.options, 'to have property', 'forbidEmptySuite', false);
+    });
+
+    it('should be chainable', function() {
+      var mocha = new Mocha(opts);
+      expect(mocha.forbidEmptySuite(), 'to be', mocha);
+    });
+  });
+
   describe('#forbidOnly()', function() {
     it('should set the forbidOnly option to true', function() {
       var mocha = new Mocha(opts);