gulp-spawn-mocha


This is a plugin for [gulp] which runs [Mocha] tests in a separate process from
the gulp process. Each time tests are run a new child process is created
meaning the test environment always starts cleanly, i.e., globals are reset as
are non-enumerable properties defined on native prototypes via
Object.defineProperty. This also means that if your tests crash the node
process (e.g., process.exit(-1).) then an error event is emitted rather than
your whole gulp process crashing (good for watching).

Usage

Usage is according to this API:

``javascript
stream.pipe(
mocha({
// options
})
);
`

This plugin uses mocha version ^6.0.0. The major version of this plugin will
match the major version of mocha, which is a peer dependency of this plugin.

The plugin accepts these special options:

- bin: a path to a mocha executable to use instead of the one this plugin
looks for by default. This is useful if you want to use a fork of mocha
which goes by a different name or a different executable altogether.
- env: the environment variables that the child process will have access to
(key-value pairs, see [child_process::fork][fork]). These variables are
merged with your current environment variables and sent to the mocha
executable.
- cwd: the working directory for the child process. This can be used to put
files that the test creates or reads from the working directory in a specific
directory, instead of the directory where you are running gulp from.
- execPath: an alternative execution path to the Node.js instance.
If not specified, by default, [child_process::fork][fork] will spawn the new
Node.js instances using the [process::execPath][execpath] of the parent process.

All other options are properly prefixed with either - or -- and passed to
the mocha executable. Any arguments which do not take a value (e.g., c,
colors, or debug) should just have a value of true. Any arguments which
have dashes in the name can be specified by using camelCase (i.e., debugBrk
for --debug-brk, inlineDiffs for --inline-diffs, etc) so you don't have
to use strings for the argument names. Please note that the gc option must
be specified as exposeGc (please see [issue #21][21]). For an example, see
this plugin's very own gulpfile.js:

`javascript
const DEBUG = process.env.NODE_ENV === "debug",
CI = process.env.CI === "true";

var gulp = require("gulp"),
mocha = require("./lib");

gulp.task("test", function() {
return gulp.src(["test/*.test.js"], { read: false }).pipe(
mocha({
debugBrk: DEBUG,
r: "test/setup.js",
R: CI ? "spec" : "nyan",
istanbul: !DEBUG
})
);
});

gulp.task("default", ["test"], function() {
gulp.watch("{lib,test}/*", ["test"]);
});
`

With this setup the nyan reporter will be used in development and the spec
reporter will be used in CI (Travis sets the CI environment variable to
true automatically).

The default task will execute tests and watch for changes and execute tests
whenever a change is detected.

$3

If the value of an argument is falsy (but not 0) then it will not be passed
to mocha. This is useful, for example, if you want to enable debugging only
when a certain environment variable is true. Example:

`javascript
const DEBUG = process.env.NODE_ENV === "debug";
stream.pipe(
mocha({
debugBrk: DEBUG,
istanbul: !DEBUG
})
);
`

$3

As mentioned above an object provided underneath the env options key will
allow you to specify a custom environment. This is useful, for example, to run
your tests in a different NODE_ENV than the default. Such a gulp task would
look like this:

`javascript
var gulp = require("gulp"),
mocha = require("gulp-spawn-mocha");

gulp.task("test", function() {
return gulp.src(["test/*.test.js"]).pipe(
mocha({
env: { NODE_ENV: "test" }
})
);
});
`

These variables are merged with your current environment variables and sent to
the mocha executable.

$3

Because of the nature of this plugin launching an external process to run tests,
the standard coverage plugins for gulp will not work with this module. Starting
in version 0.4.0 [Istanbul] is included in order to enable code coverage
reports without having to instrument code on disk. You can use it by passing the
istanbul option.

Set istanbul to true if you want to use all the default settings:

`javascript
gulp.task("test", function() {
return gulp.src(["test/*.test.js"]).pipe(
mocha({
istanbul: true
})
);
});
`

This will launch a process equivilant to:

`
istanbul cover -- _mocha
`

The default settings of Istanbul output to a directory in the cwd called
coverage.

If you want to pass options to Istanbul, you can do that as well:

`javascript
gulp.task("test", function() {
return gulp.src(["test/*.test.js"]).pipe(
mocha({
istanbul: {
dir: "path/to/custom/output/directory"
}
})
);
});
`

This will launch a process equivilant to:

`
istanbul cover --dir path/to/custom/output/directory -- _mocha
`

This will output to a directory called path/to/custom/output/directory.

Istanbul, like mocha, supports a custom bin option so you can use a custom
fork of Istanbul:

`javascript
gulp.task("test", function() {
return gulp.src(["test/*.test.js"]).pipe(
mocha({
istanbul: {
dir: "path/to/custom/output/directory",
bin: require.resolve("isparta") + "/bin/isparta"
}
})
);
});
`

This will launch a process equivilant to:

`
./node_modules/isparta/bin/isparta cover --dir path/to/custom/output/directory -- _mocha
`

#### Publishing Coverage Reports

Assuming you are using [Travis] for CI and [Coveralls] for
publishing code coverage reports it is very easy to automatically have Travis
publish to Coveralls when tests are run successfully. First make sure you
install and save the coveralls module as a dev dependency:

`
npm i --save-dev coveralls
`

Then edit your .travis.yml to have an after_success command:

`yaml
language: node_js
node_js:
- "0.11"
- "0.10"
after_success: ./node_modules/.bin/coveralls --verbose < coverage/lcov.info
`

The coveralls module requires no additional configuration to publish to
Coveralls as long as both Travis and Coveralls are configured for the same
_public_ repository. See [node-coveralls][ncov] for more details.

$3

You can pass output option to write a report to a writeable stream. If
output is a string then a writeable stream will be created with output as
its path. Note, if you are using istanbul, your reports content may contain
istanbul's result.

Use file path:

`js
gulp.task("test", function() {
return gulp.src(["test/*.test.js"], { read: false }).pipe(
mocha({
debugBrk: DEBUG,
r: "test/setup.js",
R: CI ? "spec" : "nyan",
istanbul: !DEBUG,
output: "result.log"
})
);
});
`

Use file stream:

`js
gulp.task("test", function() {
return gulp.src(["test/*.test.js"], { read: false }).pipe(
mocha({
debugBrk: DEBUG,
r: "test/setup.js",
R: CI ? "spec" : "nyan",
istanbul: !DEBUG,
output: fs.createWriteStream("result.log", { flags: "w" })
})
);
});
`

This or gulp-mocha?

The original gulp-mocha is fine in most circumstances. If you need your
tests to run as a separate process (or a separate process is simply your
preference for the reasons specified above) or you need to use a custom
version of Mocha (e.g., a fork with bug fixes or custom functionality) then
you should use this plugin.

License

MIT

[gulp]: http://gulpjs.com/ "gulp.js"
[mocha]: http://mochajs.org/ "Mocha"
[fork]: https://nodejs.org/api/child_process.html#child_process_child_process_fork_modulepath_args_options "child_process::fork"
[execpath]: https://nodejs.org/api/process.html#process_process_execpath "process::execPath"
[istanbul]: https://github.com/gotwarlost/istanbul "Istanbul"
[travis]: https://travis-ci.org/ "Travis CI"
[coveralls]: https://coveralls.io/ "Coveralls"
[ncov]: https://github.com/nickmerwin/node-coveralls "node-coveralls"
[21]: https://github.com/knpwrs/gulp-spawn-mocha/issues/21 "Issue 21: Setting gc option calls mocha --gc instead of mocha -gc`"