dlv_test: add a basic test for dap command (#1899)

cmd/dlv/dlv_test.go

@@ -8,6 +8,7 @@ import (
 	"go/ast"
 	"go/token"
 	"go/types"
+	"io"
 	"io/ioutil"
 	"os"
 	"os/exec"
@@ -20,6 +21,7 @@ import (
 
 	protest "github.com/go-delve/delve/pkg/proc/test"
 	"github.com/go-delve/delve/pkg/terminal"
+	"github.com/go-delve/delve/service/dap/daptest"
 	"github.com/go-delve/delve/service/rpc2"
 
 	"golang.org/x/tools/go/packages"
@@ -507,3 +509,45 @@ func TestTypecheckRPC(t *testing.T) {
 		t.Errorf("%d errors", errcount)
 	}
 }
+
+// TestDap verifies that a dap server can be started and shut down.
+func TestDap(t *testing.T) {
+	const listenAddr = "127.0.0.1:40575"
+
+	dlvbin, tmpdir := getDlvBin(t)
+	defer os.RemoveAll(tmpdir)
+
+	cmd := exec.Command(dlvbin, "dap", "--log-output=dap", "--log", "--listen", listenAddr)
+	stdout, err := cmd.StdoutPipe()
+	assertNoError(err, t, "stdout pipe")
+	stderr, err := cmd.StderrPipe()
+	assertNoError(err, t, "stderr pipe")
+	if err := cmd.Start(); err != nil {
+		t.Fatalf("could not start dap instance: %v", err)
+	}
+
+	scanOut := bufio.NewScanner(stdout)
+	scanErr := bufio.NewScanner(stderr)
+	// Wait for the debug server to start
+	scanOut.Scan()
+	listening := "DAP server listening at: " + listenAddr
+	if scanOut.Text() != listening {
+		cmd.Process.Kill() // release the port
+		t.Fatalf("Unexpected stdout:\ngot  %q\nwant %q", scanOut.Text(), listening)
+	}
+	go func() {
+		for scanErr.Scan() {
+			t.Log(scanErr.Text())
+		}
+	}()
+
+	// Connect a client and request shutdown.
+	client := daptest.NewClient(listenAddr)
+	client.DisconnectRequest()
+	client.ExpectDisconnectResponse(t)
+	if _, err := client.ReadMessage(); err != io.EOF {
+		t.Errorf("got %q, want \"EOF\"\n", err)
+	}
+	client.Close()
+	cmd.Wait()
+}