Mock underscore in jasmine/angular test











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1
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In a component, I have the following method:



import _ from 'underscore';


@Component({
selector: 'hello-selector',
templateUrl: './hello.component.html'
)}
export class Hello implements OnInit{

...
public arrayHello(): Array {
return _.chain(...)
...
}
...

ngOnInit(): void {
myarray = this.arrayHello();
}


The default test case in the angular spec file failed with the error




TypeError: Cannot read property 'chain' of undefined




How to Mock underscore in order to deal with this error?



I already tried the following but it does not seems to be the right way: spyOn(_, 'chain').and.callFake((f => f()));










share|improve this question




























    up vote
    1
    down vote

    favorite












    In a component, I have the following method:



    import _ from 'underscore';


    @Component({
    selector: 'hello-selector',
    templateUrl: './hello.component.html'
    )}
    export class Hello implements OnInit{

    ...
    public arrayHello(): Array {
    return _.chain(...)
    ...
    }
    ...

    ngOnInit(): void {
    myarray = this.arrayHello();
    }


    The default test case in the angular spec file failed with the error




    TypeError: Cannot read property 'chain' of undefined




    How to Mock underscore in order to deal with this error?



    I already tried the following but it does not seems to be the right way: spyOn(_, 'chain').and.callFake((f => f()));










    share|improve this question


























      up vote
      1
      down vote

      favorite









      up vote
      1
      down vote

      favorite











      In a component, I have the following method:



      import _ from 'underscore';


      @Component({
      selector: 'hello-selector',
      templateUrl: './hello.component.html'
      )}
      export class Hello implements OnInit{

      ...
      public arrayHello(): Array {
      return _.chain(...)
      ...
      }
      ...

      ngOnInit(): void {
      myarray = this.arrayHello();
      }


      The default test case in the angular spec file failed with the error




      TypeError: Cannot read property 'chain' of undefined




      How to Mock underscore in order to deal with this error?



      I already tried the following but it does not seems to be the right way: spyOn(_, 'chain').and.callFake((f => f()));










      share|improve this question















      In a component, I have the following method:



      import _ from 'underscore';


      @Component({
      selector: 'hello-selector',
      templateUrl: './hello.component.html'
      )}
      export class Hello implements OnInit{

      ...
      public arrayHello(): Array {
      return _.chain(...)
      ...
      }
      ...

      ngOnInit(): void {
      myarray = this.arrayHello();
      }


      The default test case in the angular spec file failed with the error




      TypeError: Cannot read property 'chain' of undefined




      How to Mock underscore in order to deal with this error?



      I already tried the following but it does not seems to be the right way: spyOn(_, 'chain').and.callFake((f => f()));







      angular mocking underscore.js karma-jasmine






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 19 at 10:02









      Philipp Meissner

      1,86911531




      1,86911531










      asked Nov 19 at 9:51









      billyjov

      658314




      658314
























          1 Answer
          1






          active

          oldest

          votes

















          up vote
          0
          down vote













          You can create mock Object for underscore.



          import _ from './test-data/UnderscoreMock';


          And use UnderscoreMock:



          ./test-data/UnderscoreMock



          export default const _ {
          chain: () => {}
          ....
          }


          and set UnderscoreMock in component.



          Second you can use spyOn into component.



          spyOn(INSTANCE_COMPONENT, "chain"); 





          share|improve this answer





















          • always get an undefined
            – billyjov
            Nov 19 at 10:13










          • can trying const spyChain = (window._, 'chain').and.callFake(() => {})
            – Konstantin Okhotnick
            Nov 19 at 10:16










          • and expect(spyChain.chain).toHaveBeenCalled();
            – Konstantin Okhotnick
            Nov 19 at 10:18










          • not working yet for the case
            – billyjov
            Nov 19 at 10:21










          • Yes, I think you need to wrap up chain in method or check value how you get with chain
            – Konstantin Okhotnick
            Nov 19 at 12:37











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          1 Answer
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          active

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          active

          oldest

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          up vote
          0
          down vote













          You can create mock Object for underscore.



          import _ from './test-data/UnderscoreMock';


          And use UnderscoreMock:



          ./test-data/UnderscoreMock



          export default const _ {
          chain: () => {}
          ....
          }


          and set UnderscoreMock in component.



          Second you can use spyOn into component.



          spyOn(INSTANCE_COMPONENT, "chain"); 





          share|improve this answer





















          • always get an undefined
            – billyjov
            Nov 19 at 10:13










          • can trying const spyChain = (window._, 'chain').and.callFake(() => {})
            – Konstantin Okhotnick
            Nov 19 at 10:16










          • and expect(spyChain.chain).toHaveBeenCalled();
            – Konstantin Okhotnick
            Nov 19 at 10:18










          • not working yet for the case
            – billyjov
            Nov 19 at 10:21










          • Yes, I think you need to wrap up chain in method or check value how you get with chain
            – Konstantin Okhotnick
            Nov 19 at 12:37















          up vote
          0
          down vote













          You can create mock Object for underscore.



          import _ from './test-data/UnderscoreMock';


          And use UnderscoreMock:



          ./test-data/UnderscoreMock



          export default const _ {
          chain: () => {}
          ....
          }


          and set UnderscoreMock in component.



          Second you can use spyOn into component.



          spyOn(INSTANCE_COMPONENT, "chain"); 





          share|improve this answer





















          • always get an undefined
            – billyjov
            Nov 19 at 10:13










          • can trying const spyChain = (window._, 'chain').and.callFake(() => {})
            – Konstantin Okhotnick
            Nov 19 at 10:16










          • and expect(spyChain.chain).toHaveBeenCalled();
            – Konstantin Okhotnick
            Nov 19 at 10:18










          • not working yet for the case
            – billyjov
            Nov 19 at 10:21










          • Yes, I think you need to wrap up chain in method or check value how you get with chain
            – Konstantin Okhotnick
            Nov 19 at 12:37













          up vote
          0
          down vote










          up vote
          0
          down vote









          You can create mock Object for underscore.



          import _ from './test-data/UnderscoreMock';


          And use UnderscoreMock:



          ./test-data/UnderscoreMock



          export default const _ {
          chain: () => {}
          ....
          }


          and set UnderscoreMock in component.



          Second you can use spyOn into component.



          spyOn(INSTANCE_COMPONENT, "chain"); 





          share|improve this answer












          You can create mock Object for underscore.



          import _ from './test-data/UnderscoreMock';


          And use UnderscoreMock:



          ./test-data/UnderscoreMock



          export default const _ {
          chain: () => {}
          ....
          }


          and set UnderscoreMock in component.



          Second you can use spyOn into component.



          spyOn(INSTANCE_COMPONENT, "chain"); 






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 19 at 10:02









          Konstantin Okhotnick

          946718




          946718












          • always get an undefined
            – billyjov
            Nov 19 at 10:13










          • can trying const spyChain = (window._, 'chain').and.callFake(() => {})
            – Konstantin Okhotnick
            Nov 19 at 10:16










          • and expect(spyChain.chain).toHaveBeenCalled();
            – Konstantin Okhotnick
            Nov 19 at 10:18










          • not working yet for the case
            – billyjov
            Nov 19 at 10:21










          • Yes, I think you need to wrap up chain in method or check value how you get with chain
            – Konstantin Okhotnick
            Nov 19 at 12:37


















          • always get an undefined
            – billyjov
            Nov 19 at 10:13










          • can trying const spyChain = (window._, 'chain').and.callFake(() => {})
            – Konstantin Okhotnick
            Nov 19 at 10:16










          • and expect(spyChain.chain).toHaveBeenCalled();
            – Konstantin Okhotnick
            Nov 19 at 10:18










          • not working yet for the case
            – billyjov
            Nov 19 at 10:21










          • Yes, I think you need to wrap up chain in method or check value how you get with chain
            – Konstantin Okhotnick
            Nov 19 at 12:37
















          always get an undefined
          – billyjov
          Nov 19 at 10:13




          always get an undefined
          – billyjov
          Nov 19 at 10:13












          can trying const spyChain = (window._, 'chain').and.callFake(() => {})
          – Konstantin Okhotnick
          Nov 19 at 10:16




          can trying const spyChain = (window._, 'chain').and.callFake(() => {})
          – Konstantin Okhotnick
          Nov 19 at 10:16












          and expect(spyChain.chain).toHaveBeenCalled();
          – Konstantin Okhotnick
          Nov 19 at 10:18




          and expect(spyChain.chain).toHaveBeenCalled();
          – Konstantin Okhotnick
          Nov 19 at 10:18












          not working yet for the case
          – billyjov
          Nov 19 at 10:21




          not working yet for the case
          – billyjov
          Nov 19 at 10:21












          Yes, I think you need to wrap up chain in method or check value how you get with chain
          – Konstantin Okhotnick
          Nov 19 at 12:37




          Yes, I think you need to wrap up chain in method or check value how you get with chain
          – Konstantin Okhotnick
          Nov 19 at 12:37


















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