trace: fix getting family for the method (#3216)

trace.go

@@ -41,9 +41,6 @@ func methodFamily(m string) string {
 	if i := strings.Index(m, "/"); i >= 0 {
 		m = m[:i] // remove everything from second slash
 	}
-	if i := strings.LastIndex(m, "."); i >= 0 {
-		m = m[i+1:] // cut down to last dotted component
-	}
 	return m
 }
 

trace_test.go

@@ -0,0 +1,50 @@
+/*
+ *
+ * Copyright 2019 gRPC 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 grpc
+
+import (
+	"testing"
+)
+
+func (s) TestMethodFamily(t *testing.T) {
+	cases := []struct {
+		desc             string
+		method           string
+		wantMethodFamily string
+	}{
+		{
+			desc:             "No leading slash",
+			method:           "pkg.service/method",
+			wantMethodFamily: "pkg.service",
+		},
+		{
+			desc:             "Leading slash",
+			method:           "/pkg.service/method",
+			wantMethodFamily: "pkg.service",
+		},
+	}
+
+	for _, ut := range cases {
+		t.Run(ut.desc, func(t *testing.T) {
+			if got := methodFamily(ut.method); got != ut.wantMethodFamily {
+				t.Fatalf("methodFamily(%s) = %s, want %s", ut.method, got, ut.wantMethodFamily)
+			}
+		})
+	}
+}