Exercise Solutions: Unit Testing

Automatic Testing to Find Errors

  1. Get the sourcecode file and the test code file to talk to each other.

    1. Add two require statements.

      checkFive.spec.js:

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         const test = require('../checkFive.js');

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  1. Check that checkFive produces the correct output when passed a number less than 5.

    1. Write a descriptive test name.

      checkFive.spec.js:

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         it("returns 'num is less than 5' when num < 5.", function(){
      // test code //
   });

    1. Use expect.

      checkFive.spec.js:

      expect(output).toEqual("2 is less than 5.");

    1. Change the sourcecode file and see that the test fails.

      checkFive.js:

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         if (num > 5) {
      // sourcecode //
   }

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Try One on Your Own

  1. Set up the RPS.js and RPS.spec.js files to talk to each other.

    RPS.js:

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       module.exports = {
         whoWon: whoWon
   };

    RPS.spec.js:

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       const test = require('../RPS.js');

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  1. Two sample tests.

    RPS.spec.js:

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       describe("whoWon", function(){

      it("returns 'Player 2 wins!' if P1 = rock & P2 = paper", function(){
         let output = test.whoWon('rock','paper');
         expect(output).toEqual("Player 2 wins!");
      });

      it("returns 'Player 2 wins!' if P1 = paper & P2 = scissors", function(){
         let output = test.whoWon('paper','scissors');
         expect(output).toEqual("Player 2 wins!");
      });

      // other test cases //

   }

Typo to fix:

In RPS.js, there is a conditional block that checks if player1 plays 'scissors' and player2 plays 'rock '. The 'rock ' string contains a trailing space that should be removed.

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