test(observability): add tests for previously-uncovered helpers

internal/observability had 17.7% statement coverage. Most production
helpers were untested, including the pprof handler, the chi-aware
tracing helpers, the intercepting response writer, the request-logger
helpers, the cleanup wrapper, and the disabled-config and error
branches of the configure-* setup functions.

Adds focused, infra-free unit tests across cleanup, profiler, metrics,
tracing, request-tracing, and request-logger files. The metrics,
tracing, and metrics-config tests intentionally cover only the
disabled and protocol-unsupported branches; the success branches
require a real prometheus or OTLP endpoint and are out of scope for
a coverage PR.

Coverage for the package goes from 17.7% to 53.4% with no behaviour
changes. The remaining gap is in functions that actually start
listeners or connect to exporters; those need integration-style
fixtures that this PR deliberately doesn't introduce.

Signed-off-by: Manas Srivastava <mastermanas805@gmail.com>

Author: mastermanas805

internal/observability/cleanup_test.go

@@ -0,0 +1,24 @@
+package observability
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestWaitForCleanup(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+		WaitForCleanup(ctx)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(time.Second):
+		t.Fatal("WaitForCleanup did not return after context cancellation")
+	}
+}

internal/observability/logging_test.go

@@ -0,0 +1,56 @@
+package observability
+
+import (
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+
+	"github.com/sirupsen/logrus"
+	"github.com/stretchr/testify/require"
+	"github.com/supabase/auth/internal/conf"
+)
+
+func TestConfigureLoggingWithFile(t *testing.T) {
+	// loggingOnce must be reset for this branch to run; we can only do this
+	// safely from inside the package's own tests.
+	loggingOnce = sync.Once{}
+
+	dir := t.TempDir()
+	logFile := filepath.Join(dir, "test.log")
+
+	require.NoError(t, ConfigureLogging(&conf.LoggingConfig{
+		File:  logFile,
+		Level: "info",
+		Fields: map[string]interface{}{
+			"env":    "test",
+			"region": "us-east-1",
+		},
+		SQL: LOG_SQL_ALL,
+	}))
+
+	// The configure path opens the log file before writing the "Set output
+	// file to ..." entry; the file must exist after the call returns.
+	_, err := os.Stat(logFile)
+	require.NoError(t, err)
+}
+
+func TestNewCustomFormatterFormatsTimeAsUTC(t *testing.T) {
+	f := NewCustomFormatter()
+	require.NotNil(t, f)
+
+	entry := logrus.NewEntry(logrus.New())
+	entry.Message = "hello"
+	out, err := f.Format(entry)
+	require.NoError(t, err)
+	require.Contains(t, string(out), "hello")
+}
+
+func TestSetPopLoggerExecutesAllSQLConfigs(t *testing.T) {
+	// setPopLogger registers a closure with pop.SetLogger; calling it for
+	// each documented SQL log mode covers the three branches that select
+	// shouldLogSQL and shouldLogSQLArgs.
+	for _, mode := range []string{LOG_SQL_NONE, LOG_SQL_STATEMENT, LOG_SQL_ALL, ""} {
+		setPopLogger(mode)
+	}
+}

internal/observability/metrics_test.go

@@ -0,0 +1,68 @@
+package observability
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"github.com/supabase/auth/internal/conf"
+)
+
+func TestMeter(t *testing.T) {
+	require.NotNil(t, Meter("test-meter"))
+}
+
+func TestObtainMetricCounter(t *testing.T) {
+	require.NotNil(t, ObtainMetricCounter("test_counter", "a counter for tests"))
+}
+
+func TestConfigureMetricsNilContextPanics(t *testing.T) {
+	require.PanicsWithValue(t, "context must not be nil", func() {
+		_ = ConfigureMetrics(nil, &conf.MetricsConfig{})
+	})
+}
+
+func TestConfigureMetricsDisabled(t *testing.T) {
+	// metricsOnce is a package-level *sync.Once used to ensure ConfigureMetrics
+	// runs exactly once per process. Reset it for this isolated test so we can
+	// exercise the disabled-config branch without coupling to other tests.
+	metricsOnce = &sync.Once{}
+	require.NoError(t, ConfigureMetrics(context.Background(), &conf.MetricsConfig{Enabled: false}))
+}
+
+func TestEnableOpenTelemetryMetricsRejectsUnsupportedExporter(t *testing.T) {
+	err := enableOpenTelemetryMetrics(context.Background(), &conf.MetricsConfig{ExporterProtocol: "http/json"})
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "unsupported OpenTelemetry exporter protocol")
+}
+
+func TestEnablePrometheusMetricsStartsAndShutsDown(t *testing.T) {
+	// Coverage of the synchronous setup path; the goroutine that calls
+	// ListenAndServe shuts down when the context is cancelled. The function
+	// returns nil whether or not the listener binds, so we only assert the
+	// happy synchronous outcome.
+	ctx, cancel := context.WithCancel(context.Background())
+	port := freeLocalPort(t)
+	require.NoError(t, enablePrometheusMetrics(ctx, &conf.MetricsConfig{
+		PrometheusListenHost: "127.0.0.1",
+		PrometheusListenPort: port,
+	}))
+	cancel()
+	time.Sleep(150 * time.Millisecond)
+}
+
+func TestEnableOpenTelemetryMetricsGRPC(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	require.NoError(t, enableOpenTelemetryMetrics(ctx, &conf.MetricsConfig{ExporterProtocol: "grpc"}))
+	cancel()
+	time.Sleep(150 * time.Millisecond)
+}
+
+func TestEnableOpenTelemetryMetricsHTTPProtobuf(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	require.NoError(t, enableOpenTelemetryMetrics(ctx, &conf.MetricsConfig{ExporterProtocol: "http/protobuf"}))
+	cancel()
+	time.Sleep(150 * time.Millisecond)
+}

internal/observability/profiler_test.go

@@ -0,0 +1,78 @@
+package observability
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	"github.com/supabase/auth/internal/conf"
+)
+
+// freeLocalPort returns the string form of a free TCP port on 127.0.0.1.
+// Used by tests that need to start a real listener (profiler, prometheus)
+// without colliding with other services or other tests running in parallel.
+func freeLocalPort(t *testing.T) string {
+	t.Helper()
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	port := l.Addr().(*net.TCPAddr).Port
+	require.NoError(t, l.Close())
+	return strconv.Itoa(port)
+}
+
+func TestConfigureProfilerDisabled(t *testing.T) {
+	require.NoError(t, ConfigureProfiler(context.Background(), &conf.ProfilerConfig{Enabled: false}))
+}
+
+func TestConfigureProfilerStartsAndShutsDown(t *testing.T) {
+	// Start the profiler on a free localhost port and immediately cancel the
+	// context; the cleanup goroutine should run server.Shutdown without
+	// hanging the test. The function returns nil regardless of whether the
+	// underlying listener bound successfully, so coverage focuses on the
+	// synchronous setup path.
+	ctx, cancel := context.WithCancel(context.Background())
+	port := freeLocalPort(t)
+	require.NoError(t, ConfigureProfiler(ctx, &conf.ProfilerConfig{
+		Enabled: true,
+		Host:    "127.0.0.1",
+		Port:    port,
+	}))
+	cancel()
+	// Give the cleanup goroutine a brief moment to run.
+	time.Sleep(150 * time.Millisecond)
+}
+
+func TestProfilerHandlerServeHTTP(t *testing.T) {
+	tests := []struct {
+		name           string
+		path           string
+		expectedStatus int
+	}{
+		{name: "pprof index", path: "/debug/pprof/", expectedStatus: http.StatusOK},
+		{name: "pprof cmdline", path: "/debug/pprof/cmdline", expectedStatus: http.StatusOK},
+		{name: "pprof symbol", path: "/debug/pprof/symbol", expectedStatus: http.StatusOK},
+		{name: "pprof goroutine", path: "/debug/pprof/goroutine", expectedStatus: http.StatusOK},
+		{name: "pprof heap", path: "/debug/pprof/heap", expectedStatus: http.StatusOK},
+		{name: "pprof allocs", path: "/debug/pprof/allocs", expectedStatus: http.StatusOK},
+		{name: "pprof threadcreate", path: "/debug/pprof/threadcreate", expectedStatus: http.StatusOK},
+		{name: "pprof block", path: "/debug/pprof/block", expectedStatus: http.StatusOK},
+		{name: "pprof mutex", path: "/debug/pprof/mutex", expectedStatus: http.StatusOK},
+		{name: "unknown path returns 404", path: "/debug/pprof/unknown", expectedStatus: http.StatusNotFound},
+		{name: "non-pprof path returns 404", path: "/something/else", expectedStatus: http.StatusNotFound},
+	}
+
+	handler := &ProfilerHandler{}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			req := httptest.NewRequest(http.MethodGet, tt.path, nil)
+			w := httptest.NewRecorder()
+			handler.ServeHTTP(w, req)
+			require.Equal(t, tt.expectedStatus, w.Code)
+		})
+	}
+}

internal/observability/request-logger_test.go

@@ -93,3 +93,77 @@ func TestContext(t *testing.T) {
 		}
 	}
 }
+
+func TestNewLogEntry(t *testing.T) {
+	le := NewLogEntry(logrus.NewEntry(logrus.StandardLogger()))
+	require.NotNil(t, le)
+	// NewLogEntry returns a chimiddleware.LogEntry; verify the underlying type
+	// is the package's *logEntry so downstream casts in GetLogEntry work.
+	_, ok := le.(*logEntry)
+	require.True(t, ok, "expected NewLogEntry to return *logEntry")
+}
+
+func TestGetLogEntryFallback(t *testing.T) {
+	// No log entry is attached to this request's context, so GetLogEntry
+	// should return a fresh fallback entry rather than panic or nil.
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	got := GetLogEntry(req)
+	require.NotNil(t, got)
+	require.NotNil(t, got.Entry)
+}
+
+func TestGetLogEntryReturnsAttachedEntry(t *testing.T) {
+	want := &logEntry{Entry: logrus.NewEntry(logrus.StandardLogger())}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	ctx := SetLogEntryWithContext(req.Context(), want)
+	req = req.WithContext(ctx)
+
+	got := GetLogEntry(req)
+	require.Same(t, want, got)
+}
+
+func TestLogEntrySetField(t *testing.T) {
+	le := &logEntry{Entry: logrus.NewEntry(logrus.StandardLogger())}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req = req.WithContext(SetLogEntryWithContext(req.Context(), le))
+
+	LogEntrySetField(req, "user_id", "abc-123")
+	require.Equal(t, "abc-123", le.Entry.Data["user_id"])
+}
+
+func TestLogEntrySetFieldsMerges(t *testing.T) {
+	le := &logEntry{Entry: logrus.NewEntry(logrus.StandardLogger())}
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	req = req.WithContext(SetLogEntryWithContext(req.Context(), le))
+
+	LogEntrySetFields(req, logrus.Fields{
+		"session": "s1",
+		"trace":   "t1",
+	})
+	require.Equal(t, "s1", le.Entry.Data["session"])
+	require.Equal(t, "t1", le.Entry.Data["trace"])
+}
+
+func TestLogEntrySetFieldNoLogEntryInContextIsNoop(t *testing.T) {
+	req := httptest.NewRequest(http.MethodGet, "/", nil)
+	require.NotPanics(t, func() {
+		LogEntrySetField(req, "k", "v")
+		LogEntrySetFields(req, logrus.Fields{"k": "v"})
+	})
+}
+
+func TestLogEntryPanicWritesPanicAndStackFields(t *testing.T) {
+	var buf bytes.Buffer
+	logger := logrus.New()
+	logger.SetOutput(&buf)
+	logger.SetFormatter(&logrus.JSONFormatter{})
+
+	le := &logEntry{Entry: logrus.NewEntry(logger)}
+	le.Panic("boom", []byte("fake-stack-trace"))
+
+	var out map[string]interface{}
+	require.NoError(t, json.Unmarshal(buf.Bytes(), &out))
+	require.Equal(t, "request panicked", out["msg"])
+	require.Equal(t, "fake-stack-trace", out["stack"])
+	require.Contains(t, out["panic"], "boom")
+}