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Testing Pipes and Directives

Testing Pipes and Directives

Learn how to test pipes and directives in Angular.

We'll cover the following...

Testing pipes

In this lesson, we will learn how to test a pipe. Previously, we learned that a pipe is a TypeScript class that implements the PipeTransform interface. It exposes a transform method, which is usually synchronous, which means it is straightforward to test. The list.pipe.ts file contains a pipe that converts a comma-separated string into a list:

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import { Pipe, PipeTransform } from '@angular/core';
@Pipe({
  name: 'list'
})
export class ListPipe implements PipeTransform {
  transform(value: string): string[] {
    return value.split(',');
  }
}

Writing a test for it is simple. The only thing that we need to ...