Harden local runtime safety and error handling

cmd/qfs/request_logger_test.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/gin-gonic/gin"
+)
+
+func TestRequestLoggerDoesNotLogResponseBody(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	var logBuffer bytes.Buffer
+	previousLogger := slog.Default()
+	slog.SetDefault(slog.New(slog.NewTextHandler(&logBuffer, &slog.HandlerOptions{})))
+	defer slog.SetDefault(previousLogger)
+
+	router := gin.New()
+	router.Use(requestLogger())
+	router.GET("/fail", func(c *gin.Context) {
+		_ = c.Error(errors.New("root cause"))
+		c.JSON(http.StatusBadRequest, gin.H{"error": "do not log this body"})
+	})
+
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/fail?debug=1", nil)
+	router.ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400, got %d", rec.Code)
+	}
+
+	logOutput := logBuffer.String()
+	if !strings.Contains(logOutput, "request failed") {
+		t.Fatalf("expected request failure log, got %q", logOutput)
+	}
+	if strings.Contains(logOutput, "do not log this body") {
+		t.Fatalf("response body leaked into logs: %q", logOutput)
+	}
+	if !strings.Contains(logOutput, "root cause") {
+		t.Fatalf("expected error details in logs, got %q", logOutput)
+	}
+}