unused: rewrite test

unused/testdata/src/basic/basic.go

@@ -0,0 +1,83 @@
+package basic
+
+// -- used as argument
+
+type Sender interface {
+	Send(msg string) error
+}
+
+func Ping(sender Sender) error {
+	return sender.Send("ping")
+}
+
+// -- used as struct field
+
+type MessageHandler interface {
+	HandleMessage(msg string) error
+}
+
+type Consumer struct {
+	Handler MessageHandler
+}
+
+// -- used as type cast
+
+type Commitable interface {
+	Commit() error
+}
+
+func CommitAll(msgs []any) error {
+	for _, msg := range msgs {
+		c, ok := msg.(Commitable)
+		if !ok {
+			continue
+		}
+
+		if err := c.Commit(); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// grouped type declaration
+
+type (
+	Executor interface { // want "^interface 'Executor' is declared but not used within the package$"
+		Execute() error
+	}
+
+	Job struct {
+		Name string
+	}
+
+	Runner interface { // want "^interface 'Runner' is declared but not used within the package$"
+		Run() error
+	}
+)
+
+// -- used as return value
+
+type Calculator interface {
+	Calc() int
+}
+
+type Task struct {
+	A int
+	B int
+}
+
+func (t *Task) Calc() int {
+	return t.A + t.B
+}
+
+func Add(a, b int) Calculator {
+	return &Task{A: a, B: b}
+}
+
+// -- single type declaration
+
+type Writer interface { // want "^interface 'Writer' is declared but not used within the package$"
+	Write(b []byte) error
+}