How to mock formbuilder in Jasmine?

@hailie 

To mock a form builder in Jasmine, you can use the spyOn function to create a mock object that allows you to control the behavior of the form builder. Here is an example of how you might do this:

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import { FormBuilder } from '@angular/forms';

describe('MyComponent', () => {
  let formBuilder: FormBuilder;

  beforeEach(() => {
    formBuilder = new FormBuilder();
    spyOn(formBuilder, 'group').and.returnValue({});
  });

  it('should create a form group', () => {
    const formGroup = formBuilder.group({});
    expect(formGroup).toEqual({});
  });
});

In this example, we create a mock form builder using the spyOn function and specify that the group method should return an empty object. We can then use the mock form builder in our test to create a form group and make assertions about its behavior.

You can also use the and.callThrough method to make the mock form builder pass through to the real implementation of the group method, if you want to test the actual behavior of the form builder.

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spyOn(formBuilder, 'group').and.callThrough();

I hope this helps! Let me know if you have any questions.

@hailie 

This example is using Jasmine and Angular framework to mock Angular FormBuilder. You can create a mock form builder by using the SpyObject class from the @ng-mocks library. Here's an example of how you can mock the form builder in Jasmine:

1. Install the @ng-mocks library:

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npm install --save-dev @ng-mocks/mock

1. Import the necessary dependencies:

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import { TestBed } from '@angular/core/testing';
import { FormBuilder, FormGroup, ReactiveFormsModule } from '@angular/forms';
import { MockBuilder, MockInstance, MockRender } from '@ng-mocks/ng-mocks';

1. Create a mock of the form builder:

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describe('MyComponent', () => {
  let formBuilder: FormBuilder;

  beforeEach(() => {
    formBuilder = MockInstance(FormBuilder, () => ({
      group: jasmine.createSpy('group').and.returnValue({})
    }));
  });

  it('should create a form group', () => {
    const formGroup = formBuilder.group({});
    expect(formGroup).toEqual({});
  });
});

In this example, we use the MockInstance function from @ng-mocks/ng-mocks to create a mock of the FormBuilder class. We then use the jasmine.createSpy function to create a spy for the group method of the form builder and set its return value to an empty object. This allows us to control the behavior of the form builder and test the component that uses it.

Finally, we can use the mock form builder in our test and make assertions about its behavior.

Note: You may need to configure your testing module with the ReactiveFormsModule using the MockBuilder function from @ng-mocks/ng-mocks to avoid any potential errors with the form builder.

I hope this helps! Let me know if you have any further questions.