# How to test a command?

1. Open the respective command test suite, ex: CreateCommandTestSuite.scala

2. Grab the CommandFixture, provide the Input (if any) & verify the post & pre conditions.

   For example:

   1. To verify if all the post conditions pass given the right input:

     test("create first lottery", Tag("create"), ptest) {
       grab[CreateCommandFixture]
         .given()
         .when(Input(lotteryName = "TestLottery", amount = 200))
         .expectPostPass
     }
   

   2. To test a pre-condition logic:

      test("create duplicate lottery", Tag("duplicate"), ntest) {
          LotteryWriter().drop()
          grab[CreateCommandFixture]
            .given(LotteryCreated("TestLottery", 100))
            .when(Input("TestLottery", 200))
            .expectPreFail("NewLotteryName")
        }
      

3. Run the testcase:

   [LotteryDomain] testOnly *CreateCommandTestSuite -- -n create
   

4. To retrieve the output of the command use retrieveOutput

   
   
   
   
   
   

    

   
   
   
   

   test("create first lottery", Tag("create"), ptest) {
       val commandResult = grab[CreateCommandFixture]
         .given()
         .when(Input(lotteryName = "TestLottery", amount = 200))
         .expectPostPass
         .retrieveOutput
       assert(commandResult.result == "TestLottery created successfully")
     }
   

Best practice:

• Ensure there are enough unit tests i.e.
  • Atleast one testcase to ensure the command does what it is supposed to do (ptest) & verify the post passes
  • Atleast one testcase for every pre-condition (ntest)