Potential undefined objects in Angular unit testing

While working on unit testing, I encountered the following error:

'Object is possibly 'undefined''

 it('should set the dataSource filter to the provided argument', () => {
  component.applyFilter('filterValue');
   expect(this.dataSource.filter).toEqual('filterValue');
  })

it('should set the dataSource filter to the provided argument', () => {
   component.applyFilter('filterValue');
   expect(this.DMDataSource.filter).toEqual('filterValue');
 })

I am seeing an error within the expect(this) part. Can you help me identify the mistake here?

Your assistance would be greatly appreciated.

angulartypescriptunit-testingjasminekarma-jasmine

Answer №1

It's best to utilize component.dataSource instead of this.dataSource within the expect block

Make sure to assess the dataSource specified inside the component object

it('should update the dataSource filter with the provided argument', () => {
  component.applyFilter('filterValue');
   expect(component.dataSource.filter).toEqual('filterValue');
})

it('should update the dataSource filter with the provided argument', () => {
   component.applyFilter('filterValue');
   expect(component.DMDataSource.filter).toEqual('filterValue');
})

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