Gherkin-testcafe NPM

gherkin-testcafe

Run TestCafé tests with the Gherkin syntax

What it does

TestCafé is a tool for automating end-to-end tests for websites. This package provides a compatibility layer so that BDD-style tests can be run with TestCafé using the Gherkin syntax. Please note that there was a plan to officially support Gherkin syntax in TestCafé. However it has been cancelled.

Installation

Install gherkin-testcafe and cucumber1 via npm or yarn:

npm i gherkin-testcafe @cucumber/cucumber

yarn add gherkin-testcafe @cucumber/cucumber

You may also install gherkin-testcafe globally in order to be able to use the CLI without npx.

TestCafé is a peer dependency of this package. There is no need to publish a new version of this package everytime a new version of TC is released, but this does mean there is a risk of compatibility issues. To make sure you are using compatible versions, please refer to this (new and incomplete) compatibility matrix

1 This package internally uses Cucumber.js to parse step definitions. You will need it to define steps (see Writing step definitions).

CLI usage

Use the gherkin-testcafe just like you use TestCafé's CLI. Just replace testcafe with gherkin-testcafe and load all JS and feature files:

gherkin-testcafe firefox,IE tests/**/*.js tests/**/*.feature

Use --help command to see all options:

gherkin-testcafe --help

All TestCafé CLI options are supported.

Additionally, you can specify:

Tags to run (see Tags):

The --tags parameter can take a list of tags to filter scenarios in (or out) of the test run.

Including tag:

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --tags @TAG

This runs all scenarios that have @TAG

Excluding tag:

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --tags ~@TAG

This runs all scenarios that don't have @TAG

List of tags:

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --tags @TAG1,@TAG2

This runs all scenarios that have @TAG1 or @TAG2

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --tags @TAG1,~@TAG2

This runs all scenarios that have @TAG1 and not @TAG2

and operation:

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --tags "@TAG1 and @TAG2"

This runs all scenarios that have @TAG1 and @TAG2

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --tags "@TAG1 and ~@TAG2, @TAG2 and ~@TAG1"

This runs all scenarios that have either @TAG1 or @TAG2, not both

Custom parameter types, (see Cucumber Expressions)

  gherkin-testcafe firefox tests/**/*.js tests/**/*.feature --param-type-registry-file ./a-file-that-exports-a-parameter-type-registry.js

Programming interface

To get more fine grained control over the testrun, you can use the programming interface. It is very similar to TestCafé's programming interface. It supports all options of TestCafé's runner class, except it replaces src with steps and specs.

You can use the programming interface almost exactly like TestCafé's. Just replace the import of testcafe by gherkin-testcafe and load all step and spec files:

- const createTestCafe = require('testcafe');
+ const createTestCafe = require('gherkin-testcafe');

module.exports = async () => {
    const testcafe = await createTestCafe();
    const runner = await testcafe.createRunner();
    const remoteConnection = await testcafe.createBrowserConnection();

    return runner
-       .src('test.js')
+       .src(['steps/**/*.js', 'specs/**/*.feature'])
        .browsers([remoteConnection, 'chrome'])
        .run();
};

You can use all other runner methods, that you like as well (e.g. filter, screenshots and reporter).

Special cases

Some features couldn't be implemented in the exact same way they work for regular TestCafé. This is mostly due to the fact that our compiler handles the fixture and test objects internally. This means that fixture and test methods are not available outside of the gherkin compiler.

Fixture and test name

Fixture and test name can be accessed from the tests through the testRun property of the TestController object.

Given(/some step/, async (t: TestController) => {
  const { name: testName, fixture } = t.testRun.test;
  const { name: fixtureName } = fixture;
});

Metadata

The fixture.meta() and test.meta() methods cannot be used directly. Instead, the compiler will automatically add the name of the feature and the tags attached to it in the fixture metadata. The test metadata will only contain the attached tags.

The fixture metadata is accessible from within the beforeAll and afterAll hooks.

The test and fixture metadata can be accessed from the tests through the testRun property of the TestController object.

Given(/some step/, async (t: TestController) => {
  const testMeta = t.testRun.test.meta;
  const fixtureMeta = t.testRun.test.fixture.meta;
});

Fixture context

The fixture context can be accessed from the tests through the testRun property of the TestController object.

Given(/some step/, async (t: TestController) => {
  const { fixtureCtx } = t.testRun;
});

It is best practice to avoid sharing data between tests, so the fixture context should only ever be read. Writing into the fixtureCtx property of the test run is not forbidden, but should be avoided.

The fixture context is also accessible from within the beforeAll and afterAll hooks.

Basic HTTP Authentication

TestCafé doesn't display nor handle the browser's dialog boxes, so Basic HTTP Authentication can only be achieved by programmatically setting the Authorization header properly, then accessing the page.

To do this, regular TestCafé exposes the fixture.httpAuth and test.httpAuth methods.

For the same reason as before, in gherkin-testcafe, neither are accessible outside of the compiler. To work around that, you may create featureFileName.credentials.js next to featureFileName.feature that exports the needed credentials.

That file being JS, you can get the credentials from any kind of source you'd like, as long as the end result is properly exported with the property names that httpAuth is expecting.

The credentials are applied to all the tests in the feature. They will not be applied to any other feature, each feature file requires its own dedicated credential file.

At the moment, httpAuth can only be used at the feature level.

Writing step definitions

To write step definitions, import Given, When and/ or Then from cucumber2:

import { Given, When, Then } from '@cucumber/cucumber';

Given(/some precondition/, async (t) => {
  // The first argument of Given, When and Then will be a regex that matches the step.
  // The second argument is a function that takes TestCafé's test controller object as a parameter.
});

When(/something (.+) happens/, async (t, params) => {
  // Captured parameters in the step regex will be passed as the second argument to the test implementation.
  // "When Something great happens" will call this function with `["great"]` as `params`.
});

When(/something (.+) and (.+) happens/, async (t, [param1, param2]) => {
  // You can use regular array destructuring to access params directly.
  // "When Something great and awesome happens" will result in `"great"` as `param1` and `"awesome"` as `param2`.
});

Then(/an assertion takes place/, async (t) => {
  // Test code is the same as TestCafé's test function accepts.
  await t.expect(true).ok();
});

Then(
  'use Cucumber Expressions to get {int}, {float}, {word}, {string}, etc',
  async (t, [intParam, floatParam, singleWordParam, stringParam]) => {
    // You can use "Cucumber Expressions" instead of regex to get the parameters in the desired types.
    // It's also possible to add custom parameter types if needed.
    await t.expect(typeof intParam).eql('number');
  }
);

2 You need to install Cucumber.js as a dependency (see Installation).

It is worth noting, that for the test runner, Given, When and Then are the same thing. You can define

Given(/some step/, async (t) => {
  // Test code
});

and use it as

When some step

Please refer to the examples directory for more examples.

Supported gherkin features and limitations

This package supports a wide range of gherkin features. Most notable features are:

Features (Gherkin feature keyword): Will be transformed into a TestCafé fixture.
Scenarios (Gherkin scenario keyword): Will be transformed into a TestCafé test.
Backgrounds (Gherkin background keyword): Background steps are prepended to Scenario/ Scenario outline steps. Before hooks are run before background steps.
Scenario outlines (Gherkin Scenario Outline and Examples keywords): Will transform every example into on TestCafé test.
Tags/ Hooks: See Tags and Hooks.
Cucumber Expressions

Cucumber Expressions

Besides using Regular Expressions, you can also use Cucumber Expressions in your steps, and have support for Optional text, Alternative text and getting parameters in their desired types. The Cucumber built-in parameter types are supported by default.

It's also possible to add custom parameter types by creating a file that exports a cucumberExpressions.ParameterTypeRegistry, and passing this file's path to the CLI with --param-type-registry-file or to the Programming interface with the parameterTypeRegistryFile method.

Example:

Create a ParameterTypeRegistry (e.g. myCustomParamRegistry.js):

import { ParameterTypeRegistry, ParameterType } from '@cucumber/cucumber-expressions';

class Color {
  constructor(name) {
    this.name = `${name} color`;
  }
}

const registry = new ParameterTypeRegistry();

registry.defineParameterType(
  new ParameterType(
    'color', // name of the parameter
    /red|blue|yellow/, // regexp used to match
    Color, // the parameter's type
    (name) => new Color(name) // transformer function
  )
);

module.exports = registry;

Use it in a step:

When I am searching for the blue color on Google

Retrieve the value in the step implementation:

When('I am searching for the {color} color on Google', async (t, [color]) => {
  console.log(color.name); // blue color
});

Configure the runner to use your custom ParameterTypeRegistry:
```
runner.parameterTypeRegistryFile('./myCustomParamRegistry.js');
```
Note: Do not set --param-type-registry-file CLI parameter when running tests through the programming interface as it is internally used to pass the path of the ParameterTypeRegistry file to the gherkin compiler.

Please refer to the examples directory, and the official Cucumber Expressions documentation for more details.

Hooks

In contrast to Cucumber.js' hooks, they are implemented differently in this package. Hooks in this package are always asynchronous. Instead of taking a callback parameter to end the hook, this package's hooks return a promise. Once this promise fulfills, the hook is considered done. The order of hook execution is not guaranteed to follow any rules. So be careful when using multiple hooks for the same scenario.

`Before` and `After`

Before/After hooks run before or after each test (i.e. scenario). Each hook implementation gets TestCafé's test controller object as a parameter.

import { Before } from '@cucumber/cucumber';

Before('@tag1', async (t) => {
  // do something
  // e.g. write to t.ctx or read from t.fixtureCtx
});

Untagged hooks are run before/ after each test.

`BeforeAll` and `AfterAll`

BeforeAll/AfterAll hooks run before or after each fixture (i.e. feature). Each hook implementation gets TestCafé's fixture context. See Sharing Variables Between Fixture Hooks and Test Code documentation for more details.

import { BeforeAll } from '@cucumber/cucumber';

BeforeAll(async (ctx, meta) => {
  // do something with the context and/or the meta
});

Data tables

When steps have a data table, they are passed an object with methods that can be used to access the data.

with column headers
- hashes: returns an array of objects where each row is converted to an object (column header is the key)
- rows: returns the table as a 2-D array, without the first row
without column headers
- raw: returns the table as a 2-D array
- rowsHash: returns an object where each row corresponds to an entry (first column is the key, second column is the value)

See the examples directory for an example.

Step reporting

By default, the reporter used by TestCafé is spec. TestCafé has no reason to handle the concept of "step" because it's a notion that is specific to gherkin.

To work around that:

The metadata of a test now contains the full list of steps that compose the scenario it's based on. In case of failure of a step, its index is also added to the metadata.
A custom reporter (gtc-reporter-spec) has been added to the project. It is automatically used instead of spec as the default reporter for gherkin-testcafe. Note that spec remains usable by simply using the reporter option provided by TestCafé: bash gherkin-testcafe chrome ./tests/* --reporter spec If you use the API, js runner.reporter("spec")
Custom internal reporters have also been created based on list and minimal. The gtc reporters behave in exactly the same way as their TestCafé counterparts, except that the steps are part of the output, with highlighing indicating which ones succeeded, which ones failed, and which ones didn't run. diff + ✓ Given some step that succeeded - ✖ When some step that failed # - Then some step that didn't run
```
To use one of this package's internal reporters, use its name in the reporter option:
```bash
gherkin-testcafe chrome ./tests/* --reporter gtc-reporter-list
gherkin-testcafe chrome ./tests/* --reporter gtc-reporter-minimal
gherkin-testcafe chrome ./tests/* --reporter gtc-reporter-spec # unnecessary as it is the default behavior
```
```

Note that other official reporters could be adapted in the future.

Implement / Adapt a custom reporter

If you are using a custom reporter and want to use or display the step information, all you need to do is access the metadata from your reporter's methods.

Fortunately, accessing metadata is built-in behavior for normal TestCafé reporters: TestCafé will pass the metadata object to your test reporting function as the third argument.

The properties that are dedicated to this feature are steps and failIndex. Each step in the steps array has two properties: type and text.

Representation:

{
    "failIndex": 2,
    "steps": [
        { "type": "Context", "keyword": "Given", "prefix": "Background", "text": "some background step"}
        { "type": "Context", "keyword": "Given", "text": "some step that succeeded"},
        { "type": "Action", "keyword": "When", "text": "some step that failed"},
        { "type": "Action", "keyword": "And", "text": "some step that didn't run"},
        { "type": "Outcome", "keyword": "Then", "text": "some other step that didn't run"}
    ]
}

Usage example:

const reportTestDone = function (name, testRunInfo, meta) {
    meta.steps.forEach((step, index) => {
        let color;
        let symbol;
        if (index < meta.failIndex) {
            color = 'green';
            symbol = this.symbols.ok;
        } else if (index === meta.failIndex) {
            color = 'red';
            symbol = this.symbols.err;
        } else {
            color = 'grey';
            symbol = '-';
        }
        this.write(this.chalk[color](symbol));
        if (step.prefix) {
            this.write(this.chalk.white(`${step.prefix}:`));
        }
        this.write(this.chalk[color](`${step.keyword}${step.text}`));
        this.newline();
    });
},

Using Typescript and ESnext features

With gherkin-testcafe, you can use Typescript and ESnext features (like es module import statements) the same way you can use them in regular TestCafé tests. In fact, it actually uses TestCafé's compilers to compile Typescript and ESNext files.

Please refer to TestCafé's Typescript support manual page to see how you can customize compiler options and which compiler options are used by default.

Please make sure not to install @types/cucumber! gherkin-testcafe will provide types for the cucumber module.

Unfortunately, you cannot define your custom parameter types registry file in Typescript or with ESnext features.

Contributing

The release branch is master.
The development branch is develop.

Always create your new branch from develop.

I'd appreciate if you would use git flow (or follow its naming conventions) but it's not mandatory.

Commits will generally not be accepted if they have not been properly formatted.

Commits

The package has commitizen as a dev dependency. To create the proper commit, use yarn gitcommit and follow the prompts.

Do not hesitate to create an issue if you need help.

Releases

The package has standard-version as a dev dependency. It makes version management pretty easy, as long as commits have been properly formatted (hence the obligation to use commitizen)