Using Jasmine to spy on a function without an object

Question

I m new to Jasmine and have just started using it  I have a library js file with lots of functions which are not associated with any object  i e  are global   How do I go about spying on these functions   I tried using window document as the object  but the spy did not work even though the function was called  I also tried wrapping it in a fake object as follows    var fakeElement       fakeElement fakeMethod   myFunctionName  spyOn fakeElement   fakeMethod      and test with  expect fakeElement fakeMethod  toHaveBeenCalled      This does not work either as the spy did not work

User · Answer

There is  2 alternative which I use  for jasmine 2   This one is not quite explicit because it seems that the function is actually a fake   test   createSpy   and callFake test      The second more verbose  more explicit  and  cleaner    test   createSpy  testSpy   test  and callThrough      -  jasmine source code to see the second argument

User · Answer

My answer differs slightly to  FlavorScape in that I had a single  default export  function in the imported module  I did the following   import   as functionToTest from  whatever-lib    const fooSpy   spyOn functionToTest   default

User · Answer

If you are defining your function   function test         Then  this is equivalent to   window test   function           in the browser       So spyOn window   test   should work   If that is not  you should also be able to   test   jasmine createSpy      If none of those are working  something else is going on with your setup   I don t think your fakeElement technique works because of what is going on behind the scenes  The original globalMethod still points to the same code  What spying does is proxy it  but only in the context of an object  If you can get your test code to call through the fakeElement it would work  but then you d be able to give up global fns

User · Answer

A very simple way   import   as myFunctionContainer from  whatever-lib    const fooSpy   spyOn myFunctionContainer   myFunc

User · Answer

import   as saveAsFunctions from  file-saver                       let saveAs              beforeEach      gt                    saveAs   jasmine createSpy  saveAs                               it  should generate the excel on sample request details page        gt                    spyOn saveAsFunctions   saveAs   and callFake saveAs                   expect saveAsFunctions saveAs  toHaveBeenCalled                     This worked for me

User · Answer

TypeScript users   I know the OP asked about javascript  but for any TypeScript users who come across this who want to spy on an imported function  here s what you can do   In the test file  convert the import of the function from this   import  foo  from     foo functions    x   foo y     To this   import   as FooFunctions from     foo functions    x   FooFunctions foo y     Then you can spy on FooFunctions foo     spyOn FooFunctions   foo   and callFake              expect FooFunctions foo  toHaveBeenCalled

[javascript] Using Jasmine to spy on a function without an object

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