chore: improve test coverage in pubsub instrumentation

instrumentation/cloud.google.com/go/pubsub/push_test.go

@@ -6,6 +6,8 @@ package pubsub_test
 import (
 	"bytes"
 	"context"
+	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
@@ -190,3 +192,186 @@ func (alwaysReadyClient) SendEvent(event *instana.EventData) error          { re
 func (alwaysReadyClient) SendSpans(spans []instana.Span) error              { return nil }
 func (alwaysReadyClient) SendProfiles(profiles []autoprofile.Profile) error { return nil }
 func (alwaysReadyClient) Flush(context.Context) error                       { return nil }
+
+// errorReader is a custom io.Reader that always returns an error
+type errorReader struct{}
+
+func (errorReader) Read(p []byte) (n int, err error) {
+	return 0, errors.New("forced read error")
+}
+
+// TestTracingHandlerFunc_ReadBodyError tests error handling when reading request body fails
+func TestTracingHandlerFunc_ReadBodyError(t *testing.T) {
+	recorder := instana.NewTestRecorder()
+	c := instana.InitCollector(&instana.Options{
+		AgentClient: alwaysReadyClient{},
+		Recorder:    recorder,
+	})
+	defer instana.ShutdownCollector()
+
+	var numCalls int
+	h := pubsub.TracingHandlerFunc(c, "/", func(w http.ResponseWriter, req *http.Request) {
+		numCalls++
+	})
+
+	rec := httptest.NewRecorder()
+
+	// Create a request with a body that will fail to read
+	req := httptest.NewRequest(http.MethodPost, "/", errorReader{})
+
+	h(rec, req)
+
+	// Verify that the handler returned an error and didn't call the wrapped handler
+	assert.Equal(t, http.StatusInternalServerError, rec.Result().StatusCode)
+	assert.Equal(t, 0, numCalls)
+}
+
+// TestTracingHandlerFunc_InvalidJSON tests handling of malformed JSON messages
+func TestTracingHandlerFunc_InvalidJSON(t *testing.T) {
+	recorder := instana.NewTestRecorder()
+	c := instana.InitCollector(&instana.Options{
+		AgentClient: alwaysReadyClient{},
+		Recorder:    recorder,
+	})
+	defer instana.ShutdownCollector()
+
+	var numCalls int
+	h := pubsub.TracingHandlerFunc(c, "/", func(w http.ResponseWriter, req *http.Request) {
+		numCalls++
+	})
+
+	rec := httptest.NewRecorder()
+
+	// Create a request with invalid JSON
+	invalidJSON := []byte(`{"message": "this is not valid pubsub message format"}`)
+	req := httptest.NewRequest(http.MethodPost, "/", bytes.NewReader(invalidJSON))
+
+	h(rec, req)
+
+	// Verify that the handler falls back to regular HTTP tracing
+	assert.Equal(t, http.StatusOK, rec.Result().StatusCode)
+	assert.Equal(t, 1, numCalls)
+
+	spans := recorder.GetQueuedSpans()
+	require.Len(t, spans, 1)
+	assert.Equal(t, "g.http", spans[0].Name) // Regular HTTP span, not PubSub span
+}
+
+// TestTracingHandlerFunc_InvalidSubscriptionFormat tests handling of invalid subscription formats
+func TestTracingHandlerFunc_InvalidSubscriptionFormat(t *testing.T) {
+	recorder := instana.NewTestRecorder()
+	c := instana.InitCollector(&instana.Options{
+		AgentClient: alwaysReadyClient{},
+		Recorder:    recorder,
+	})
+	defer instana.ShutdownCollector()
+
+	var numCalls int
+	h := pubsub.TracingHandlerFunc(c, "/", func(w http.ResponseWriter, req *http.Request) {
+		numCalls++
+	})
+
+	rec := httptest.NewRecorder()
+
+	// Create a request with invalid subscription format
+	invalidSubscription := []byte(`{
+		"message": {
+			"attributes": {},
+			"messageId": "136969346945"
+		},
+		"subscription": "invalid-subscription-format"
+	}`)
+	req := httptest.NewRequest(http.MethodPost, "/", bytes.NewReader(invalidSubscription))
+
+	h(rec, req)
+
+	// Verify that the handler falls back to regular HTTP tracing
+	assert.Equal(t, http.StatusOK, rec.Result().StatusCode)
+	assert.Equal(t, 1, numCalls)
+
+	spans := recorder.GetQueuedSpans()
+	require.Len(t, spans, 1)
+	assert.Equal(t, "g.http", spans[0].Name) // Regular HTTP span, not PubSub span
+}
+
+// TestParsePathResourceIDExported tests the parsePathResourceID function indirectly
+// by creating test cases that will exercise different paths in the subscription parsing logic
+func TestParsePathResourceIDExported(t *testing.T) {
+	recorder := instana.NewTestRecorder()
+	c := instana.InitCollector(&instana.Options{
+		AgentClient: alwaysReadyClient{},
+		Recorder:    recorder,
+	})
+	defer instana.ShutdownCollector()
+
+	tests := []struct {
+		name          string
+		subscription  string
+		expectSuccess bool
+	}{
+		{
+			name:          "Valid subscription format",
+			subscription:  "projects/myproject/subscriptions/mysubscription",
+			expectSuccess: true,
+		},
+		{
+			name:          "Missing projects prefix",
+			subscription:  "notprojects/myproject/subscriptions/mysubscription",
+			expectSuccess: false,
+		},
+		{
+			name:          "Missing subscriptions part",
+			subscription:  "projects/myproject/notsubscriptions/mysubscription",
+			expectSuccess: false,
+		},
+		{
+			name:          "Empty string",
+			subscription:  "",
+			expectSuccess: false,
+		},
+		{
+			name:          "Just projects prefix",
+			subscription:  "projects/",
+			expectSuccess: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// We'll test the parsePathResourceID function indirectly through startConsumePushSpan
+			payload := []byte(fmt.Sprintf(`{
+				"message": {
+					"attributes": {},
+					"messageId": "136969346945"
+				},
+				"subscription": "%s"
+			}`, tt.subscription))
+
+			var numCalls int
+			h := pubsub.TracingHandlerFunc(c, "/", func(w http.ResponseWriter, req *http.Request) {
+				numCalls++
+			})
+
+			rec := httptest.NewRecorder()
+			req := httptest.NewRequest(http.MethodPost, "/", bytes.NewReader(payload))
+
+			h(rec, req)
+
+			if tt.expectSuccess {
+				// Should create a PubSub span
+				assert.Equal(t, 1, numCalls)
+				spans := recorder.GetQueuedSpans()
+				require.Len(t, spans, 1)
+				assert.Equal(t, "gcps", spans[0].Name)
+			} else {
+				// Should fall back to HTTP span
+				assert.Equal(t, 1, numCalls)
+				spans := recorder.GetQueuedSpans()
+				require.Len(t, spans, 1)
+				assert.Equal(t, "g.http", spans[0].Name)
+			}
+
+			// Create a new recorder for each test case instead of resetting
+		})
+	}
+}