Add unit tests to ensure custom tags parsing is correct

observability/exporting.go

@@ -22,6 +22,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"os"
 
 	gcplogging "cloud.google.com/go/logging"
 	grpclogrecordpb "google.golang.org/grpc/observability/internal/logging"
@@ -54,10 +55,14 @@ func newCloudLoggingExporter(ctx context.Context, projectID string) (*cloudLoggi
 		return nil, fmt.Errorf("failed to create cloudLoggingExporter: %v", err)
 	}
 	defer logger.Infof("Successfully created cloudLoggingExporter")
+	customTags := getCustomTags(os.Environ())
+	if len(customTags) != 0 {
+		logger.Infof("Adding custom tags: %+v", customTags)
+	}
 	return &cloudLoggingExporter{
 		projectID: projectID,
 		client:    c,
-		logger:    c.Logger("grpc", gcplogging.CommonLabels(getCustomTags())),
+		logger:    c.Logger("grpc", gcplogging.CommonLabels(customTags)),
 	}, nil
 }
 

observability/tags.go

@@ -19,20 +19,22 @@
 package observability
 
 import (
-	"os"
 	"strings"
 )
 
-const envPrefixCustomTags = "GRPC_OBSERVABILITY_"
+const (
+	envPrefixCustomTags = "GRPC_OBSERVABILITY_"
+	envPrefixLen        = len(envPrefixCustomTags)
+)
 
-func getCustomTags() map[string]string {
+func getCustomTags(envs []string) map[string]string {
 	m := make(map[string]string)
-	for _, e := range os.Environ() {
+	for _, e := range envs {
 		if !strings.HasPrefix(e, envPrefixCustomTags) {
 			continue
 		}
-		if i := strings.Index(e, "="); i >= 0 {
-			m[e[:i]] = e[i+1:]
+		if i := strings.Index(e, "="); i > envPrefixLen {
+			m[e[envPrefixLen:i]] = e[i+1:]
 		}
 	}
 	return m

observability/tags_test.go

@@ -0,0 +1,64 @@
+/*
+ *
+ * Copyright 2018 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 observability
+
+import (
+	"reflect"
+	"testing"
+)
+
+// TestGetCustomTags tests the normal tags parsing
+func (s) TestGetCustomTags(t *testing.T) {
+	var (
+		input = []string{
+			"GRPC_OBSERVABILITY_APP_NAME=app1",
+			"GRPC_OBSERVABILITY_DATACENTER=us-west1-a",
+			"GRPC_OBSERVABILITY_smallcase=OK",
+		}
+		expect = map[string]string{
+			"APP_NAME":   "app1",
+			"DATACENTER": "us-west1-a",
+			"smallcase":  "OK",
+		}
+	)
+	result := getCustomTags(input)
+	if !reflect.DeepEqual(result, expect) {
+		t.Errorf("result [%+v] != expect [%+v]", result, expect)
+	}
+}
+
+// TestGetCustomTagsInvalid tests the sunny day path of the custom tags parsing
+func (s) TestGetCustomTagsInvalid(t *testing.T) {
+	var (
+		input = []string{
+			"GRPC_OBSERVABILITY_APP_NAME=app1",
+			"GRPC_OBSERVABILITY=foo",
+			"GRPC_OBSERVABILITY_=foo",
+			"GRPC_STUFF=foo",
+			"STUFF_GRPC_OBSERVABILITY_=foo",
+		}
+		expect = map[string]string{
+			"APP_NAME": "app1",
+		}
+	)
+	result := getCustomTags(input)
+	if !reflect.DeepEqual(result, expect) {
+		t.Errorf("result [%+v] != expect [%+v]", result, expect)
+	}
+}