Referenceerror: spyon is not defined

The “ReferenceError: spyOn is not defined” error typically occurs when the spyOn function is not recognized by the JavaScript runtime environment. The spyOn function is provided by the Jasmine testing framework and is used to create a “spy” for method stubbing and behavior verification.

To resolve this error, make sure that you have properly included the Jasmine framework in your project. You can do this by downloading the Jasmine library from the official website or including it via a package manager like npm or yarn.

Below is an example of how to use spyOn in Jasmine:

      // Assume we have a simple calculator module with an add method:
      const calculator = {
        add: (a, b) => a + b
      };
      
      // We can create a spy for the add method:
      spyOn(calculator, 'add');
      
      // Now we can use the spy to stub the add method:
      calculator.add.and.returnValue(10);
      
      // We can also verify the number of times add method was called:
      expect(calculator.add).toHaveBeenCalled();
      
      // Rest of the test code...
    

Make sure that you have included the Jasmine library correctly and are using the spyOn function from within the scope where it was imported or defined. Additionally, check for any typos or syntax errors in your code that could be causing the spyOn function to be unrecognized.