How to Measure the Length of an Undefined Value in Jasmine Angular Unit Tests

Question

How to Measure the Length of an Undefined Value in Jasmine Angular Unit Tests

Here's a function that I have:

  updateParts(enviromentContainsAllParts: PartsContainsAllParts): Observable<boolean> {
    const enviroment = cloneDeep(this.enviroment);
    enviroment.containsAllPart = enviromentContainsAllParts.containsAllPart;
    for (let index = 0; index < enviromentContainsAllParts.parts.length; index++) {
      const currentPart = enviromentContainsAllParts.parts[index];
      enviroment.parts.push({
        size: currentPart.sizeOfEnviroment
      });
    }
    return of(true);
  }

When attempting to unit test this function:

it('should have changed the environment parts', () => {
  // GIVEN
  const enviroment = cloneDeep(fakeCurrentEnvironment);
  service.environment = environment;
  // WHEN
  service.updateParts(building).subscribe(data =>
    expect(data).toBeTruthy()
  );
  // THEN
});

An error was encountered:

TypeError: Cannot read property 'length' of undefined

Can anyone help me identify what I might be doing wrong?

angular typescript unit-testing jasmine

Answer 1

Answer №1

It seems like the

environmentContainsAllParts.parts

is not defined within the building.

Consider trying the following code snippet:

it('should update environment parts', (done) => { // add done here to notify jasmine when the test is completed
  // GIVEN
  const mockEnvironmentContainsAllParts = {
    containsAllPart: {
      
    }
    parts: [] // customize this array as needed for simulation purposes
  };
  const environment = cloneDeep(fakeCurrentEnvironment);
  service.environment = environment;
  // WHEN
  service.updateParts(mockEnvironmentContainsAllParts).subscribe(data => // provide the mock instead of building
    expect(data).toBeTruthy();
    done(); // inform jasmine that the task is complete and we have verified the subscription and assertion
  );
  // THEN
});

Answer 2

It seems like the

environmentContainsAllParts.parts

is not defined within the building.

Consider trying the following code snippet:

it('should update environment parts', (done) => { // add done here to notify jasmine when the test is completed
  // GIVEN
  const mockEnvironmentContainsAllParts = {
    containsAllPart: {
      
    }
    parts: [] // customize this array as needed for simulation purposes
  };
  const environment = cloneDeep(fakeCurrentEnvironment);
  service.environment = environment;
  // WHEN
  service.updateParts(mockEnvironmentContainsAllParts).subscribe(data => // provide the mock instead of building
    expect(data).toBeTruthy();
    done(); // inform jasmine that the task is complete and we have verified the subscription and assertion
  );
  // THEN
});

How to Measure the Length of an Undefined Value in Jasmine Angular Unit Tests

Answer №1

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