Gno debugging section

003-debug-gno-code/README.md

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+# 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 
+
+<details>
+    <summary>Solution (only if you're stuck!)</summary>
+
+```go
+func Push(s string) {
+    q = append(q, s)
+}
+
+func Pop() string {
+    if len(q) == 0 {
+        return ""
+    }
+    s := q[0]
+    q = q[1:]
+    return s
+}
+```
+
+</details>

003-debug-gno-code/queue.gno

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+package queue
+
+var q []string
+
+// Push appends s to q.
+func Push(s string) {
+	// TODO
+}
+
+// Pop removes the first element of q and returns it.
+// If q is empty, Pop returns an empty string.
+func Pop() string {
+	// TODO
+	return ""
+}

003-debug-gno-code/queue_test.gno

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+package queue
+
+import "testing"
+
+func TestQueue(t *testing.T) {
+	// Push 2 items
+	Push("alice")
+	Push("bob")
+	// Call Pop() 3 times
+	// Third time should return an empty string because the queue is empty
+	for i, expected := range []string{"alice", "bob", ""} {
+		res := Pop()
+		if res != expected {
+			t.Errorf("Pop()#%d want %q, got %q", i, expected, res)
+		}
+	}
+}