Add ability to pass in test files to be ran before positional files via --file (mochajs#3190)

* Add ability to pass in test files to be ran before positional files via --file

Fixes mochajs#3181

Author: hswolff

bin/_mocha

@@ -78,6 +78,11 @@ const exit = code => {
  */
 const list = str => str.split(/ *, */);
 
+/**
+ * Parse multiple flag.
+ */
+const collect = (val, memo) => memo.concat(val);
+
 /**
  * Hide the cursor.
  */
@@ -199,7 +204,8 @@ program
   .option('--delay', 'wait for async suite definition')
   .option('--allow-uncaught', 'enable uncaught errors to propagate')
   .option('--forbid-only', 'causes test marked with only to fail the suite')
-  .option('--forbid-pending', 'causes pending tests and test marked with skip to fail the suite');
+  .option('--forbid-pending', 'causes pending tests and test marked with skip to fail the suite')
+  .option('--file <file>', 'include a file to be ran during the suite', collect, []);
 
 program._name = 'mocha';
 
@@ -497,13 +503,16 @@ if (!files.length) {
 }
 
 // resolve
-
+let fileArgs = program.file.map(path => resolve(path));
 files = files.map(path => resolve(path));
 
 if (program.sort) {
   files.sort();
 }
 
+// add files given through --file to be ran first
+files = fileArgs.concat(files);
+
 // --watch
 
 let runner;

docs/index.md

@@ -736,6 +736,7 @@ Mocha supports the `err.expected` and `err.actual` properties of any thrown `Ass
     --debug-brk                             enable node's debugger breaking on the first line
     --globals <names>                       allow the given comma-delimited global [names]
     --es_staging                            enable all staged features
+    --file <file>                           include a file to be ran during the suite [file]
     --harmony<_classes,_generators,...>     all node --harmony* flags are available
     --preserve-symlinks                     Instructs the module loader to preserve symbolic links when resolving and caching modules
     --icu-data-dir                          include ICU data
@@ -853,6 +854,10 @@ Disables timeouts. Equivalent to `--timeout 0`.
 
 Specify the "slow" test threshold, defaulting to 75ms. Mocha uses this to highlight test-cases that are taking too long.
 
+### `--file <file>`
+
+Add a file you want included first in a test suite. This is useful if you have some generic setup code that must be included within the test suite. The file passed is not affected by any other flags (`--recursive` or `--sort` have no effect). Accepts multiple `--file` flags to include multiple files, the order in which the flags are given are the order in which the files are included in the test suite. Can also be used in `mocha.opts`.
+
 ### `-g, --grep <pattern>`
 
 The `--grep` option when specified will trigger mocha to only run tests matching the given `pattern` which is internally compiled to a `RegExp`.

test/integration/fixtures/options/file-alpha.fixture.js

@@ -0,0 +1,13 @@
+'use strict';
+
+describe('alpha', function () {
+  it('should be executed first', function () {
+    if (global.beta !== undefined) {
+      throw new Error('alpha was not executed first');
+    }
+
+    if (global.theta !== undefined) {
+      throw new Error('alpha was not executed first');
+    }
+  });
+});

test/integration/fixtures/options/file-beta.fixture.js

@@ -0,0 +1,11 @@
+'use strict';
+
+describe('beta', function () {
+  it('should be executed second', function () {
+    global.beta = 1;
+
+    if (global.theta !== undefined) {
+      throw new Error('beta was not executed second');
+    }
+  });
+});

test/integration/fixtures/options/file-theta.fixture.js

@@ -0,0 +1,7 @@
+'use strict';
+
+describe('theta', function () {
+  it('should be executed third', function () {
+    global.theta = 1;
+  });
+});

test/integration/helpers.js

@@ -129,7 +129,12 @@ module.exports = {
    * @param {Function} done - Callback
    * @param {string} cwd - Current working directory for mocha run, optional
    */
-  invokeMocha: invokeMocha
+  invokeMocha: invokeMocha,
+
+  /**
+   * Resolves the path to a fixture to the full path.
+   */
+  resolveFixturePath: resolveFixturePath
 };
 
 function invokeMocha (args, fn, cwd) {

test/integration/options.spec.js

@@ -2,8 +2,10 @@
 
 var path = require('path');
 var assert = require('assert');
-var run = require('./helpers').runMochaJSON;
-var directInvoke = require('./helpers').invokeMocha;
+var helpers = require('./helpers');
+var run = helpers.runMochaJSON;
+var directInvoke = helpers.invokeMocha;
+var resolvePath = helpers.resolveFixturePath;
 var args = [];
 
 describe('options', function () {
@@ -91,6 +93,53 @@ describe('options', function () {
     });
   });
 
+  describe('--file', function () {
+    it('should run tests passed via file first', function (done) {
+      args = ['--file', resolvePath('options/file-alpha.fixture.js')];
+
+      run('options/file-beta.fixture.js', args, function (err, res) {
+        if (err) {
+          done(err);
+          return;
+        }
+        assert.equal(res.stats.pending, 0);
+        assert.equal(res.stats.passes, 2);
+        assert.equal(res.stats.failures, 0);
+
+        assert.equal(res.passes[0].fullTitle,
+          'alpha should be executed first');
+        assert.equal(res.code, 0);
+        done();
+      });
+    });
+
+    it('should run multiple tests passed via file first', function (done) {
+      args = [
+        '--file', resolvePath('options/file-alpha.fixture.js'),
+        '--file', resolvePath('options/file-beta.fixture.js')
+      ];
+
+      run('options/file-theta.fixture.js', args, function (err, res) {
+        if (err) {
+          done(err);
+          return;
+        }
+        assert.equal(res.stats.pending, 0);
+        assert.equal(res.stats.passes, 3);
+        assert.equal(res.stats.failures, 0);
+
+        assert.equal(res.passes[0].fullTitle,
+          'alpha should be executed first');
+        assert.equal(res.passes[1].fullTitle,
+          'beta should be executed second');
+        assert.equal(res.passes[2].fullTitle,
+          'theta should be executed third');
+        assert.equal(res.code, 0);
+        done();
+      });
+    });
+  });
+
   describe('--delay', function () {
     before(function () {
       args = ['--delay'];