Engine: builtin command 'commands' returns a list of registered commands

Docker-DCO-1.1-Signed-off-by: Solomon Hykes <solomon@docker.com> (github: shykes)

engine/engine_test.go

@@ -1,6 +1,7 @@
 package engine
 
 import (
+	"bytes"
 	"io/ioutil"
 	"os"
 	"path"
@@ -63,6 +64,24 @@ func TestJob(t *testing.T) {
 	}
 }
 
+func TestEngineCommands(t *testing.T) {
+	eng := newTestEngine(t)
+	defer os.RemoveAll(eng.Root())
+	handler := func(job *Job) Status { return StatusOK }
+	eng.Register("foo", handler)
+	eng.Register("bar", handler)
+	eng.Register("echo", handler)
+	eng.Register("die", handler)
+	var output bytes.Buffer
+	commands := eng.Job("commands")
+	commands.Stdout.Add(&output)
+	commands.Run()
+	expected := "bar\ncommands\ndie\necho\nfoo\n"
+	if result := output.String(); result != expected {
+		t.Fatalf("Unexpected output:\nExpected = %v\nResult   = %v\n", expected, result)
+	}
+}
+
 func TestEngineRoot(t *testing.T) {
 	tmp, err := ioutil.TempDir("", "docker-test-TestEngineCreateDir")
 	if err != nil {