add etcdutl version. make it cov-tests compatible.

etcdutl/main_test.go

@@ -0,0 +1,66 @@
+// Copyright 2017 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"log"
+	"os"
+	"strings"
+	"testing"
+)
+
+func SplitTestArgs(args []string) (testArgs, appArgs []string) {
+	for i, arg := range os.Args {
+		switch {
+		case strings.HasPrefix(arg, "-test."):
+			testArgs = append(testArgs, arg)
+		case i == 0:
+			appArgs = append(appArgs, arg)
+			testArgs = append(testArgs, arg)
+		default:
+			appArgs = append(appArgs, arg)
+		}
+	}
+	return
+}
+
+// Empty test to avoid no-tests warning.
+func TestEmpty(t *testing.T) {}
+
+/**
+ * The purpose of this "test" is to run etcdctl with code-coverage
+ * collection turned on. The technique is documented here:
+ *
+ * https://www.cyphar.com/blog/post/20170412-golang-integration-coverage
+ */
+func TestMain(m *testing.M) {
+	// don't launch etcdutl when invoked via go test
+	if strings.HasSuffix(os.Args[0], "etcdutl.test") {
+		return
+	}
+
+	testArgs, appArgs := SplitTestArgs(os.Args)
+
+	os.Args = appArgs
+
+	err := Start()
+	if err != nil {
+		log.Fatalf("etcdctl failed with: %v", err)
+	}
+
+	// This will generate coverage files:
+	os.Args = testArgs
+	m.Run()
+}