Chinotto: Custom assertions for Chai.js

Compilation of useful Chai assertions that I've written over time, migrated from the test-suites of various projects (atom-mocha in particular).

“Uh, why did you name thi-”

Because if Chai and Mocha proved anything, it's that beverages make memorable library names. Also, I enjoy Chinotto and the name on NPM was available, so I took it. Superalo.

Usage

1. Add chinotto to your project's devDependencies:

   $ npm install --save-dev chinotto

2. Then call the register() function it exports:

   require("chinotto").register();

   This automatically registers every available extension with Chai, which are used like any other BDD-style assertion:

   expect(__filename).to.be.a.file.and.to.existOnDisk;
   __dirname.should.be.a.file.and.equalPath(__dirname + "/");

   Alternatively, you can just import chinotto/register instead. This calls register() for you automatically, and makes Chinotto globally available:

   require("chinotto/register");
   
   // Define a hypothetical extension to check modification status:
   global.Chinotto.defineAssertion("modified", (subject, expected) =>
   	[subject.isModified(), "to be modified"]);
   
   // Usage:
   expect("/some/edited/file").to.be.modified;
   expect("/unedited/file").not.to.be.modified;

API reference

Extension list

• Methods
  • class()
  • equalPath()
  • hardLink()
  • pointTo()
• Properties
  • .blockDevice
  • .characterDevice
  • .device
  • .directory
  • .door
  • .drawn
  • .existOnDisk
  • .fifo
  • .file
  • .focus
  • .socket
  • .symlink

Exports

• chai: Object — Reference to the Chai module used by Chinotto.
• methods: Map — Handler functions for assertion methods, keyed by name(s)
• properties: Map — Handler functions for assertion properties, keyed by name(s)

The remaining exports are detailed under Utils:

• addMethod()
• addProperty()
• defineAssertion()
• defineAssertions()
• register()

Methods

class()/classes()

Check if an HTMLElement contains one or more CSS classes.

Parameter	Type	Attributes	Description
expected	String, Array.<String>	Variadic	An array or whitespace-delimited list of CSS class-names

Example:

document.body.should.have.class("content");
expect($(".btn.large")).to.have.classes("btn", "large");

equalPath()

Assert that two filesystem paths are logically the same.

Parameter	Type
target	String

Example:

"/bin".should.equalPath("/bin/");
"/bin/../bin".should.equalPath("/bin");

hardLink()/hardLinkOf()

Assert that two files have the same inode and device number.

Parameter	Type
target	String

Example:

"/a/huge/file".should.have.hardLink("/same/huge/file");
expect("huge.file").to.be.hardLinkOf("also.huge");

pointTo()/pointingTo()

Assert that a symbolic link points to the specified file.

Parameter	Type
target	String

Example:

"/tmp".should.be.a.symlink.pointingTo("/private/tmp");

Properties

.drawn

Assert that an HTMLElement is rendered in the DOM tree.

Example:

document.body.should.be.drawn;
document.head.should.not.be.drawn;

.focus

Assert that an HTMLElement has user focus, or contains something which does.

Example:

document.activeElement.should.have.focus;
document.createElement("div").should.not.have.focus;

.existOnDisk/.existsOnDisk

Assert that a file exists in the filesystem.

Example:

"/bin/sh".should.existOnDisk
"<>:*?\0".should.not.existOnDisk

.file/.regularFile

Assert that subject is a path pointing to a regular file.

Example:

"/bin/sh".should.be.a.file
"/bin".should.not.be.a.file

.directory

Assert that subject is a path pointing to a directory.

Example:

"/bin".should.be.a.directory
"/bin/sh".should.not.be.a.directory

.symlink/.symbolicLink

Assert that subject is a path pointing to a symbolic link.

Example:

"/usr/local/bin/node".should.be.a.symlink

.device/.deviceFile

Assert that subject is a path pointing to a device file.

“Device file” refers to either a character device or a block device, making this assertion preferable to blockDevice and characterDevice for cross-platform testing.

Example:

"/dev/zero".should.be.a.device;

.blockDevice

Assert that subject is a path pointing to a block device.

Example:

"/dev/disk0s1".should.be.a.blockDevice

.characterDevice/.charDevice

Assert that subject is a path pointing to a character device.

Example:

"/dev/null".should.be.a.characterDevice

.fifo/.namedPipe

Assert that subject is a path pointing to a FIFO (named pipe).

Example:

"/tmp/154B17E1-2BF7_IN".should.be.a.fifo

.door

Assert that subject is a path pointing to a door.

Example:

"/system/volatile/syslog_door".should.be.a.door

.socket

Assert that subject is a path pointing to a socket.

Example:

"/run/systemd/private".should.be.a.socket

Utils

addMethod()

Variant of chai.Assertion.addMethod that supports plugin aliases.

If the property already exists on the prototype, it will not be overwritten. To redefine existing methods and prototypes, use chai.util.addMethod or chai.util.overwriteMethod.

Parameter	Type
names	String, Array.<String>
fn	function

Example:

addMethod(["pointTo", "pointingTo"], function(target){ … });

addProperty()

Variant of chai.Assertion.addProperty that supports plugin aliases.

Parameter	Type
names	String, Array.<String>
fn	function

Example:

addProperty(["coloured", "colored"], fn);

defineAssertion()

Variant of defineAssertions that defines only one assertion.

Parameter	Type
names	String, Array.<String>
handler	function

defineAssertions()

Wrapper for defining simple custom Chai assertions.

Parameter	Type
spec	Object

Example:

<caption>Defining a "colour" assertion</caption>
// Typical definition:
defineAssertions({
   ["colour, coloured"](subject, expected){
       const actual = subject.colour;
       this.assert(
           actual === expected,
           "expected #{this} to be coloured #{exp}",
           "expected #{this} not to be coloured #{exp}",
           expected,
           actual
       );
   },
});

// Usage:
expect({colour: 0xFF0000}).to.have.colour(0xFF0000);
expect({colour: "red"}).not.to.be.coloured("green");

<caption>Shorthand for the above</caption>
defineAssertions({
   ["colour, coloured"](subject, expected){
       return [
           subject.colour === expected,
           "to be coloured #{exp}",
       ];
   },
});

register()

Register every available Chai extension.

Example:

import Chinotto from "./lib/index.mjs";
Chinotto.register();