ng-pom-testing

Introduction

This module compliments Angular Testbed.

ng-pom-testing provides a utility function mergeConfig for re-using Angular Testbed configuration objects, and a utility class POM for implementing the page-object-model pattern. A POM instance runs actions that are defined by a configuration object that you pass to the constructor. The constructor to the POM also accepts a context object that is passed as the first argument to the action functions. Normally, the context will include objects that were generated as part of the Angular Testbed setup -- fixtures, a dom api, and other functions.

The POM abstracts the underlying testing library (testing-library, spectator, or angular testbed) similar to how a test harness implements an api for interacting with a component instance. For example, you may want to define a single action in a test that interacts with more than a single component, or multiple components in succession like launching a modal that solicits user input -- this capability is out-of-scope for test harnesses.

The POM is particurily useful for BDD.

1. mergeConfig() - accepts a list of configuration objects. Precedence follows the es6 implementation of Object.assign(). The merge operation is "deep." Arrays are not replaced -- the entries are concatenated.

    console.log(
        mergeConfig(
            { imports: [ReactiveFormsModule]}, 
            { imports: [MaterialModule]}
        )
    )
   
    // {imports: [ReactiveFormsModule, MaterialModule]}
   

2. POM - a class for generating a configured POM implementation

   const pom = new POM({ container, detectChanges}, pomConfig);

The POM configuration object defines the actions that can be taken: the steps to be performed.

This example illustrates how to use mergeConfig and POM.

Notes

• The example implements a counter component.

  The features for the counter are implemented using three user stories. The three user stories are:

  1. The user needs a title
  2. The user needs to be able to increment a counter
  3. The user needs to see a progress control that displays the counter (the progress value). The progress control should only appear if the counter > 0.

Each successive user story adds complexity to the testing requirements.

• In the 3rd user story, a common configuration object is used when configuring Angular Testbed; the declarations and providers that are unique dependencies for the tested component are specifed in the describe block. You should adopt this pattern for your own project, in order to reduce boilerplate.

This instructional video can help you get started.