Debugging Gno code

In this section, you will learn to debug your Gno contract. As contracts aren't modifiable, it is crucial to debug them properly before their publication to the blockchain.

Debugging Gno code functions in many ways as in Go; the biggest tool at our disposal are test files. These are identified as source files whose names end with _test.go. Every function of the kind func TestXxx(t *testing.T) is automatically added as a test, run when using gno test. If the function calls t.Errorf, then it is considered failed.

• queue.gno, in this tutorial's directory 003-debug-gno-code, is a source file containing 2 stub functions Push and Pop. Your goal in this tutorial is to implement them correctly and see the tests succeed.
• queue_test.gno contains a test that checks the behavior of Pop and Push. If you implement them correctly, running gno test will succeed without errors.

Steps

• Run the test:

$ gno test . -verbose

The test will fail, because Pop and Push are currently not implemented -- if you open the queue.gno file, you will see that they just contain two // TODO comments.

• Implement Pop and Push. These need to implement a FIFO (First In, First Out) queue -- so the last element added using Push will be the first one to be removed using Pop.
• Run the test again until it succeeds

Solution (only if you're stuck!)

func Push(s string) {
    q = append(q, s)
}

func Pop() string {
    if len(q) == 0 {
        return ""
    }
    s := q[0]
    q = q[1:]
    return s
}