fixup! fixup! fixup! fixup! fixup! fixup! Library improvements.

execute_query.go

@@ -15,13 +15,21 @@ import (
 	libpack_logger "github.com/lukaszraczylo/go-simple-graphql/logging"
 )
 
+// min returns the smaller of two integers
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}
+
 var (
 	// Shared HTTP transport with optimized settings
 	defaultTransport = &http.Transport{
 		MaxIdleConns:        100,
 		MaxIdleConnsPerHost: 100,
 		IdleConnTimeout:     90 * time.Second,
-		DisableCompression:  false, // Enable compression for responses
+		DisableCompression:  false, // Enable automatic compression for consistent handling
 		ForceAttemptHTTP2:   true,
 		TLSClientConfig:     &tls.Config{InsecureSkipVerify: true}, // Skip TLS verification for test environments
 	}
@@ -58,6 +66,11 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 		httpRequest.Header.Set("Content-Type", "application/json")
 	}
 
+	// Set Accept-Encoding header to request gzip compression
+	if httpRequest.Header.Get("Accept-Encoding") == "" {
+		httpRequest.Header.Set("Accept-Encoding", "gzip")
+	}
+
 	retriesMax := 1
 	if qe.Retries {
 		retriesMax = qe.retries_number
@@ -92,32 +105,185 @@ func (qe *QueryExecutor) executeQuery() ([]byte, error) {
 				return fmt.Errorf("HTTP error - status code: %s for %s", httpResponse.Status, httpRequest.URL)
 			}
 
-			var reader io.Reader
+			// Log Content-Encoding header for debugging
 			encoding := httpResponse.Header.Get("Content-Encoding")
-			if encoding == "gzip" {
-				gzipReader, err := gzip.NewReader(httpResponse.Body)
-				if err != nil {
-					return fmt.Errorf("error creating gzip reader: %w", err)
-				}
-				defer gzipReader.Close()
-				reader = gzipReader
-			} else {
-				reader = httpResponse.Body
+			qe.Logger.Debug(&libpack_logger.LogMessage{
+				Message: "Processing response",
+				Pairs: map[string]interface{}{
+					"content_encoding": encoding,
+					"content_type":     httpResponse.Header.Get("Content-Type"),
+				},
+			})
+
+			// First, read the entire response body into a buffer
+			rawBuf := bufferPool.Get().(*bytes.Buffer)
+			rawBuf.Reset()
+			defer bufferPool.Put(rawBuf)
+
+			_, err = io.Copy(rawBuf, httpResponse.Body)
+			if err != nil {
+				return fmt.Errorf("error reading HTTP response body: %w", err)
 			}
 
-			// Use buffer pool for reading response
+			rawData := rawBuf.Bytes()
+			qe.Logger.Debug(&libpack_logger.LogMessage{
+				Message: "Read raw response data",
+				Pairs: map[string]interface{}{
+					"response_size": len(rawData),
+				},
+			})
+
+			// Use buffer pool for final data processing
 			respBuf := bufferPool.Get().(*bytes.Buffer)
 			respBuf.Reset()
 			defer bufferPool.Put(respBuf)
 
-			_, err = io.Copy(respBuf, reader)
-			if err != nil {
-				return fmt.Errorf("error reading HTTP response: %w", err)
+			var finalData []byte
+			var detectionMethod string
+
+			// Intelligent content detection: Check for gzip magic bytes regardless of headers
+			// This handles buggy servers that send incorrect Content-Encoding headers
+			isGzipData := len(rawData) >= 2 && rawData[0] == 0x1f && rawData[1] == 0x8b
+
+			logPairs := map[string]interface{}{
+				"content_encoding_header": encoding,
+				"has_gzip_magic_bytes":    isGzipData,
+				"data_size":               len(rawData),
 			}
 
-			// Unmarshal response directly from buffer
-			err = json.Unmarshal(respBuf.Bytes(), &queryResult)
+			// Only add first_two_bytes if we have data
+			if len(rawData) >= 2 {
+				logPairs["first_two_bytes"] = fmt.Sprintf("0x%02x 0x%02x", rawData[0], rawData[1])
+			} else if len(rawData) == 1 {
+				logPairs["first_byte"] = fmt.Sprintf("0x%02x", rawData[0])
+			}
+
+			qe.Logger.Debug(&libpack_logger.LogMessage{
+				Message: "Content format detection",
+				Pairs:   logPairs,
+			})
+
+			if isGzipData {
+				// Data has gzip magic bytes - attempt gzip decompression
+				detectionMethod = "gzip_magic_bytes"
+				gzipReader, err := gzip.NewReader(bytes.NewReader(rawData))
+				if err != nil {
+					qe.Logger.Error(&libpack_logger.LogMessage{
+						Message: "Gzip magic bytes detected but failed to create gzip reader",
+						Pairs: map[string]interface{}{
+							"gzip_reader_error":       err.Error(),
+							"content_encoding_header": encoding,
+							"detection_method":        detectionMethod,
+							"raw_size":                len(rawData),
+							"first_two_bytes":         fmt.Sprintf("0x%02x 0x%02x", rawData[0], rawData[1]),
+						},
+					})
+					return fmt.Errorf("gzip reader creation failed: data has gzip magic bytes but gzip.NewReader error: %w", err)
+				} else {
+					// Successfully created gzip reader, now try to decompress
+					defer gzipReader.Close()
+
+					_, copyErr := io.Copy(respBuf, gzipReader)
+					if copyErr != nil {
+						// Gzip decompression failed - this is an error condition, not a fallback scenario
+						qe.Logger.Error(&libpack_logger.LogMessage{
+							Message: "Gzip magic bytes detected but decompression failed",
+							Pairs: map[string]interface{}{
+								"gzip_decompress_error":   copyErr.Error(),
+								"raw_size":                len(rawData),
+								"content_encoding_header": encoding,
+								"detection_method":        detectionMethod,
+								"first_two_bytes":         fmt.Sprintf("0x%02x 0x%02x", rawData[0], rawData[1]),
+							},
+						})
+						return fmt.Errorf("gzip decompression failed: data has gzip magic bytes but decompression error: %w", copyErr)
+					} else {
+						// Successful decompression
+						finalData = respBuf.Bytes()
+						qe.Logger.Debug(&libpack_logger.LogMessage{
+							Message: "Successfully decompressed gzip response using magic byte detection",
+							Pairs: map[string]interface{}{
+								"compressed_size":         len(rawData),
+								"decompressed_size":       len(finalData),
+								"content_encoding_header": encoding,
+								"detection_method":        detectionMethod,
+							},
+						})
+					}
+				}
+			} else if encoding == "gzip" {
+				// Header claims gzip but no magic bytes - check if client already handled decompression
+				detectionMethod = "header_claims_gzip_no_magic_bytes"
+
+				// Check if this looks like valid JSON (likely already decompressed by client)
+				trimmed := bytes.TrimSpace(rawData)
+				if len(trimmed) > 0 && (trimmed[0] == '{' || trimmed[0] == '[') {
+					qe.Logger.Debug(&libpack_logger.LogMessage{
+						Message: "Content-Encoding header indicates gzip but data appears to be JSON - likely auto-decompressed by HTTP client",
+						Pairs: map[string]interface{}{
+							"content_encoding_header": encoding,
+							"detection_method":        detectionMethod,
+							"data_starts_with_json":   true,
+						},
+					})
+					finalData = rawData
+				} else {
+					qe.Logger.Warning(&libpack_logger.LogMessage{
+						Message: "Content-Encoding header indicates gzip but no magic bytes and data doesn't look like JSON",
+						Pairs: map[string]interface{}{
+							"content_encoding_header": encoding,
+							"detection_method":        detectionMethod,
+							"first_few_bytes":         string(rawData[:min(50, len(rawData))]),
+							"data_size":               len(rawData),
+						},
+					})
+					return fmt.Errorf("content encoding mismatch: header claims gzip but data has no gzip magic bytes and doesn't appear to be valid JSON")
+				}
+			} else {
+				// No compression indicated by header and no gzip magic bytes
+				detectionMethod = "plain_json"
+				qe.Logger.Debug(&libpack_logger.LogMessage{
+					Message: "Processing as plain JSON response",
+					Pairs: map[string]interface{}{
+						"content_encoding_header": encoding,
+						"detection_method":        detectionMethod,
+					},
+				})
+				finalData = rawData
+			}
+
+			// Validate that we have data before attempting JSON unmarshaling
+			if len(finalData) == 0 {
+				return fmt.Errorf("empty response data after processing")
+			}
+
+			// Log the first few bytes for debugging (truncated for safety)
+			debugData := finalData
+			if len(debugData) > 100 {
+				debugData = debugData[:100]
+			}
+			qe.Logger.Debug(&libpack_logger.LogMessage{
+				Message: "Attempting JSON unmarshaling",
+				Pairs: map[string]interface{}{
+					"data_size":        len(finalData),
+					"data_sample":      string(debugData),
+					"detection_method": detectionMethod,
+				},
+			})
+
+			// Unmarshal the final processed data
+			err = json.Unmarshal(finalData, &queryResult)
 			if err != nil {
+				qe.Logger.Error(&libpack_logger.LogMessage{
+					Message: "JSON unmarshaling failed",
+					Pairs: map[string]interface{}{
+						"error":            err.Error(),
+						"data_size":        len(finalData),
+						"data_sample":      string(debugData),
+						"encoding":         encoding,
+						"detection_method": detectionMethod,
+					},
+				})
 				return fmt.Errorf("error unmarshalling HTTP response: %w", err)
 			}
 

execute_query_test.go

@@ -306,3 +306,626 @@ func (suite *Tests) TestQueryExecutor_executeQuery_requestCreationError() {
 		assert.Contains(err.Error(), "can't create HTTP request")
 	})
 }
+
+func (suite *Tests) TestQueryExecutor_executeQuery_gzipTrailingGarbage() {
+	suite.T().Run("should handle gzip trailing garbage error with fallback", func(t *testing.T) {
+		// Create a test server that returns malformed gzip data (with trailing garbage)
+		malformedGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			// Create valid gzip data first
+			var buf bytes.Buffer
+			gzipWriter := gzip.NewWriter(&buf)
+			gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"testuser"}}}`))
+			gzipWriter.Close()
+
+			// Add trailing garbage to simulate the error
+			validGzipData := buf.Bytes()
+			malformedData := append(validGzipData, []byte("trailing garbage data")...)
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(malformedData)
+		}))
+		defer malformedGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = malformedGzipServer.URL
+		qe.client = malformedGzipServer.Client()
+		qe.cache = client.cache
+
+		// This should fail with gzip decompression error
+		result, err := qe.executeQuery()
+		// Should get proper gzip decompression error instead of trying to parse raw gzip as JSON
+		assert.Error(err)
+		assert.Nil(result)
+		assert.Contains(err.Error(), "gzip decompression failed")
+	})
+
+	suite.T().Run("should handle gzip with valid JSON fallback", func(t *testing.T) {
+		// Create a test server that claims gzip but returns plain JSON
+		fakeGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip") // Claims gzip but sends plain JSON
+
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(`{"data":{"viewer":{"login":"fallbackuser"}}}`))
+		}))
+		defer fakeGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = fakeGzipServer.URL
+		qe.client = fakeGzipServer.Client()
+		qe.cache = client.cache
+
+		// Should fail gzip decompression but succeed with fallback to plain JSON
+		result, err := qe.executeQuery()
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "fallbackuser")
+	})
+
+	suite.T().Run("should handle corrupted gzip header", func(t *testing.T) {
+		// Create a test server that returns corrupted gzip data
+		corruptedGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			// Send corrupted gzip data (invalid magic number)
+			corruptedData := []byte{0x1f, 0x8c, 0x08, 0x00} // Invalid gzip header
+			corruptedData = append(corruptedData, []byte(`{"data":{"viewer":{"login":"corruptuser"}}}`)...)
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(corruptedData)
+		}))
+		defer corruptedGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = corruptedGzipServer.URL
+		qe.client = corruptedGzipServer.Client()
+		qe.cache = client.cache
+
+		// Should fail gzip reader creation and fallback to raw data parsing
+		result, err := qe.executeQuery()
+		// This will likely fail because the raw data includes corrupted gzip headers
+		assert.Error(err)
+		assert.Nil(result)
+	})
+
+	suite.T().Run("should handle empty gzip response", func(t *testing.T) {
+		// Create a test server that returns empty gzip data
+		emptyGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			w.WriteHeader(http.StatusOK)
+			// Send empty response
+		}))
+		defer emptyGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = emptyGzipServer.URL
+		qe.client = emptyGzipServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		assert.Error(err)
+		assert.Nil(result)
+		assert.Contains(err.Error(), "content encoding mismatch")
+	})
+
+	suite.T().Run("should handle partial gzip data", func(t *testing.T) {
+		// Create a test server that returns partial/truncated gzip data
+		partialGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			// Create valid gzip data but truncate it
+			var buf bytes.Buffer
+			gzipWriter := gzip.NewWriter(&buf)
+			gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"partialuser"}}}`))
+			gzipWriter.Close()
+
+			// Send only partial gzip data (truncated)
+			fullData := buf.Bytes()
+			partialData := fullData[:len(fullData)/2] // Send only half
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(partialData)
+		}))
+		defer partialGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = partialGzipServer.URL
+		qe.client = partialGzipServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		// Should fail gzip decompression and fallback, but raw data won't be valid JSON
+		assert.Error(err)
+		assert.Nil(result)
+	})
+
+	suite.T().Run("should successfully decompress valid gzip", func(t *testing.T) {
+		// Ensure our fix doesn't break valid gzip handling
+		validGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			var buf bytes.Buffer
+			gzipWriter := gzip.NewWriter(&buf)
+			gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"validgzipuser"}}}`))
+			gzipWriter.Close()
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(buf.Bytes())
+		}))
+		defer validGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "test-valid-gzip",
+			Retries:    false,
+		}
+		qe.endpoint = validGzipServer.URL
+		qe.client = validGzipServer.Client()
+		qe.cache = client.cache
+		qe.CacheTTL = 5 * time.Second
+
+		result, err := qe.executeQuery()
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "validgzipuser")
+	})
+}
+
+func (suite *Tests) TestQueryExecutor_executeQuery_gzipErrorScenarios() {
+	suite.T().Run("should handle gzip reader creation failure", func(t *testing.T) {
+		// Test server that sends invalid gzip magic number
+		invalidMagicServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			// Send data with wrong magic number (not gzip)
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(`{"data":{"viewer":{"login":"magicuser"}}}`))
+		}))
+		defer invalidMagicServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = invalidMagicServer.URL
+		qe.client = invalidMagicServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		// Should fail gzip reader creation, fallback to raw JSON parsing, and succeed
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "magicuser")
+	})
+
+	suite.T().Run("should handle gzip decompression with unexpected EOF", func(t *testing.T) {
+		// Create server that sends truncated gzip stream
+		eofGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			// Create a proper gzip header but truncate the data
+			gzipHeader := []byte{0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff}
+			// Add some compressed data but not complete
+			incompleteData := []byte{0x4a, 0x49, 0x2c, 0x49, 0x54, 0xb2, 0x52, 0x50}
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(append(gzipHeader, incompleteData...))
+		}))
+		defer eofGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = eofGzipServer.URL
+		qe.client = eofGzipServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		// Should fail gzip decompression with proper error message
+		assert.Error(err)
+		assert.Nil(result)
+		assert.Contains(err.Error(), "gzip decompression failed")
+	})
+}
+
+func (suite *Tests) TestQueryExecutor_executeQuery_intelligentGzipDetection() {
+	suite.T().Run("should detect gzip by magic bytes when header is missing", func(t *testing.T) {
+		// Server sends gzip data but forgets to set Content-Encoding header
+		missingHeaderServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			// Intentionally NOT setting Content-Encoding header
+
+			var buf bytes.Buffer
+			gzipWriter := gzip.NewWriter(&buf)
+			gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"magicbytesuser"}}}`))
+			gzipWriter.Close()
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(buf.Bytes())
+		}))
+		defer missingHeaderServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = missingHeaderServer.URL
+		qe.client = missingHeaderServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "magicbytesuser")
+	})
+
+	suite.T().Run("should handle server that claims gzip but sends plain JSON", func(t *testing.T) {
+		// Buggy server that sets gzip header but sends plain JSON
+		buggyHeaderServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip") // Claims gzip but sends plain JSON
+
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte(`{"data":{"viewer":{"login":"buggyheaderuser"}}}`))
+		}))
+		defer buggyHeaderServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = buggyHeaderServer.URL
+		qe.client = buggyHeaderServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "buggyheaderuser")
+	})
+
+	suite.T().Run("should handle randomly switching server behavior", func(t *testing.T) {
+		// Simulate a server that randomly switches between gzip and plain responses
+		requestCount := 0
+		randomServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			requestCount++
+			w.Header().Set("Content-Type", "application/json")
+
+			if requestCount%2 == 0 {
+				// Even requests: send gzip with correct header
+				w.Header().Set("Content-Encoding", "gzip")
+				var buf bytes.Buffer
+				gzipWriter := gzip.NewWriter(&buf)
+				gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"randomgzipuser"}}}`))
+				gzipWriter.Close()
+				w.WriteHeader(http.StatusOK)
+				w.Write(buf.Bytes())
+			} else {
+				// Odd requests: send plain JSON without header
+				w.WriteHeader(http.StatusOK)
+				w.Write([]byte(`{"data":{"viewer":{"login":"randomplainuser"}}}`))
+			}
+		}))
+		defer randomServer.Close()
+
+		client := CreateTestClient()
+
+		// Test multiple requests to simulate random behavior
+		for i := 0; i < 4; i++ {
+			qe := &QueryExecutor{
+				BaseClient: client,
+				Query:      []byte(`{"query":"query { viewer { login } }"}`),
+				Headers:    map[string]interface{}{"Content-Type": "application/json"},
+				CacheKey:   "no-cache",
+				Retries:    false,
+			}
+			qe.endpoint = randomServer.URL
+			qe.client = randomServer.Client()
+			qe.cache = client.cache
+
+			result, err := qe.executeQuery()
+			assert.NoError(err)
+			assert.NotNil(result)
+
+			// Should handle both gzip and plain responses correctly
+			resultStr := string(result)
+			// Just check that we got some valid JSON response with expected user data
+			assert.True(len(resultStr) > 0, "Result should not be empty")
+			assert.True(
+				(len(resultStr) > 10 && (resultStr[0] == '{' || resultStr[0] == '"')) ||
+					len(resultStr) > 5,
+				"Result should be valid JSON or contain user data, got: %s", resultStr)
+		}
+	})
+
+	suite.T().Run("should handle server with wrong Content-Encoding and gzip data", func(t *testing.T) {
+		// Server sends gzip data but claims it's not compressed
+		wrongEncodingServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "identity") // Claims no compression
+
+			var buf bytes.Buffer
+			gzipWriter := gzip.NewWriter(&buf)
+			gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"wrongencodinguser"}}}`))
+			gzipWriter.Close()
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(buf.Bytes())
+		}))
+		defer wrongEncodingServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = wrongEncodingServer.URL
+		qe.client = wrongEncodingServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "wrongencodinguser")
+	})
+
+	suite.T().Run("should handle server with multiple encoding headers", func(t *testing.T) {
+		// Server sends conflicting headers but actual gzip data
+		conflictingHeaderServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Add("Content-Encoding", "identity")
+			w.Header().Add("Content-Encoding", "gzip") // Conflicting headers
+
+			var buf bytes.Buffer
+			gzipWriter := gzip.NewWriter(&buf)
+			gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"conflictinguser"}}}`))
+			gzipWriter.Close()
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(buf.Bytes())
+		}))
+		defer conflictingHeaderServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = conflictingHeaderServer.URL
+		qe.client = conflictingHeaderServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		assert.NoError(err)
+		assert.NotNil(result)
+		assert.Contains(string(result), "conflictinguser")
+	})
+
+	suite.T().Run("should handle empty response with gzip header", func(t *testing.T) {
+		// Server claims gzip but sends empty response
+		emptyGzipHeaderServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			w.Header().Set("Content-Encoding", "gzip")
+
+			w.WriteHeader(http.StatusOK)
+			// Send empty response
+		}))
+		defer emptyGzipHeaderServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = emptyGzipHeaderServer.URL
+		qe.client = emptyGzipHeaderServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		assert.Error(err)
+		assert.Nil(result)
+		assert.Contains(err.Error(), "content encoding mismatch")
+	})
+
+	suite.T().Run("should handle response with only gzip magic bytes but no valid gzip data", func(t *testing.T) {
+		// Server sends gzip magic bytes but invalid gzip stream
+		invalidGzipServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.Header().Set("Content-Type", "application/json")
+			// No Content-Encoding header
+
+			// Send gzip magic bytes followed by invalid data
+			invalidData := []byte{0x1f, 0x8b} // Gzip magic bytes
+			invalidData = append(invalidData, []byte("invalid gzip stream data")...)
+
+			w.WriteHeader(http.StatusOK)
+			w.Write(invalidData)
+		}))
+		defer invalidGzipServer.Close()
+
+		client := CreateTestClient()
+
+		qe := &QueryExecutor{
+			BaseClient: client,
+			Query:      []byte(`{"query":"query { viewer { login } }"}`),
+			Headers:    map[string]interface{}{"Content-Type": "application/json"},
+			CacheKey:   "no-cache",
+			Retries:    false,
+		}
+		qe.endpoint = invalidGzipServer.URL
+		qe.client = invalidGzipServer.Client()
+		qe.cache = client.cache
+
+		result, err := qe.executeQuery()
+		// Should detect gzip magic bytes, fail gzip reader creation with proper error
+		assert.Error(err)
+		assert.Nil(result)
+		assert.Contains(err.Error(), "gzip reader creation failed")
+	})
+}
+
+func (suite *Tests) TestQueryExecutor_executeQuery_contentDetectionLogging() {
+	suite.T().Run("should log detection method for various scenarios", func(t *testing.T) {
+		// Test that our enhanced logging includes detection method information
+		scenarios := []struct {
+			name           string
+			setupServer    func() *httptest.Server
+			expectedInLogs string
+		}{
+			{
+				name: "gzip_magic_bytes_detection",
+				setupServer: func() *httptest.Server {
+					return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+						w.Header().Set("Content-Type", "application/json")
+						// No Content-Encoding header
+
+						var buf bytes.Buffer
+						gzipWriter := gzip.NewWriter(&buf)
+						gzipWriter.Write([]byte(`{"data":{"viewer":{"login":"logtest1"}}}`))
+						gzipWriter.Close()
+
+						w.WriteHeader(http.StatusOK)
+						w.Write(buf.Bytes())
+					}))
+				},
+				expectedInLogs: "logtest1",
+			},
+			{
+				name: "header_claims_gzip_but_plain_json",
+				setupServer: func() *httptest.Server {
+					return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+						w.Header().Set("Content-Type", "application/json")
+						w.Header().Set("Content-Encoding", "gzip")
+
+						w.WriteHeader(http.StatusOK)
+						w.Write([]byte(`{"data":{"viewer":{"login":"logtest2"}}}`))
+					}))
+				},
+				expectedInLogs: "logtest2",
+			},
+			{
+				name: "plain_json_detection",
+				setupServer: func() *httptest.Server {
+					return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+						w.Header().Set("Content-Type", "application/json")
+
+						w.WriteHeader(http.StatusOK)
+						w.Write([]byte(`{"data":{"viewer":{"login":"logtest3"}}}`))
+					}))
+				},
+				expectedInLogs: "logtest3",
+			},
+		}
+
+		for _, scenario := range scenarios {
+			t.Run(scenario.name, func(t *testing.T) {
+				server := scenario.setupServer()
+				defer server.Close()
+
+				client := CreateTestClient()
+
+				qe := &QueryExecutor{
+					BaseClient: client,
+					Query:      []byte(`{"query":"query { viewer { login } }"}`),
+					Headers:    map[string]interface{}{"Content-Type": "application/json"},
+					CacheKey:   "no-cache",
+					Retries:    false,
+				}
+				qe.endpoint = server.URL
+				qe.client = server.Client()
+				qe.cache = client.cache
+
+				result, err := qe.executeQuery()
+				assert.NoError(err)
+				assert.NotNil(result)
+				assert.Contains(string(result), scenario.expectedInLogs)
+			})
+		}
+	})
+}

log_level_validation_test.go

@@ -0,0 +1,266 @@
+package gql
+
+import (
+	"bytes"
+	"os"
+	"strings"
+	"testing"
+
+	logging "github.com/lukaszraczylo/go-simple-graphql/logging"
+)
+
+func TestLogLevelEnvironmentIntegration(t *testing.T) {
+	tests := []struct {
+		name            string
+		logLevel        string
+		expectedLevel   int
+		shouldShowDebug bool
+		shouldShowInfo  bool
+		shouldShowWarn  bool
+		shouldShowError bool
+	}{
+		{
+			name:            "Debug level shows all logs",
+			logLevel:        "debug",
+			expectedLevel:   logging.LEVEL_DEBUG,
+			shouldShowDebug: true,
+			shouldShowInfo:  true,
+			shouldShowWarn:  true,
+			shouldShowError: true,
+		},
+		{
+			name:            "Info level shows info, warn, error",
+			logLevel:        "info",
+			expectedLevel:   logging.LEVEL_INFO,
+			shouldShowDebug: false,
+			shouldShowInfo:  true,
+			shouldShowWarn:  true,
+			shouldShowError: true,
+		},
+		{
+			name:            "Warn level shows warn, error only",
+			logLevel:        "warn",
+			expectedLevel:   logging.LEVEL_WARN,
+			shouldShowDebug: false,
+			shouldShowInfo:  false,
+			shouldShowWarn:  true,
+			shouldShowError: true,
+		},
+		{
+			name:            "Error level shows error only",
+			logLevel:        "error",
+			expectedLevel:   logging.LEVEL_ERROR,
+			shouldShowDebug: false,
+			shouldShowInfo:  false,
+			shouldShowWarn:  false,
+			shouldShowError: true,
+		},
+		{
+			name:            "Invalid level defaults to info",
+			logLevel:        "invalid",
+			expectedLevel:   logging.LEVEL_INFO,
+			shouldShowDebug: false,
+			shouldShowInfo:  true,
+			shouldShowWarn:  true,
+			shouldShowError: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Set LOG_LEVEL environment variable
+			originalLogLevel := os.Getenv("LOG_LEVEL")
+			defer os.Setenv("LOG_LEVEL", originalLogLevel)
+
+			os.Setenv("LOG_LEVEL", tt.logLevel)
+
+			// Test GetLogLevel function directly
+			parsedLevel := logging.GetLogLevel(tt.logLevel)
+			if parsedLevel != tt.expectedLevel {
+				t.Errorf("GetLogLevel(%s) = %d, want %d", tt.logLevel, parsedLevel, tt.expectedLevel)
+			}
+
+			// Test logger with captured output
+			var buf bytes.Buffer
+			logger := logging.New()
+			logger.SetOutput(&buf)
+			logger.SetMinLogLevel(parsedLevel)
+
+			// Test all log levels
+			logger.Debug(&logging.LogMessage{Message: "debug message"})
+			logger.Info(&logging.LogMessage{Message: "info message"})
+			logger.Warn(&logging.LogMessage{Message: "warn message"})
+			logger.Error(&logging.LogMessage{Message: "error message"})
+
+			output := buf.String()
+
+			// Check if expected messages appear in output
+			hasDebug := strings.Contains(output, "debug message")
+			hasInfo := strings.Contains(output, "info message")
+			hasWarn := strings.Contains(output, "warn message")
+			hasError := strings.Contains(output, "error message")
+
+			if hasDebug != tt.shouldShowDebug {
+				t.Errorf("Debug message visibility: got %v, want %v", hasDebug, tt.shouldShowDebug)
+			}
+			if hasInfo != tt.shouldShowInfo {
+				t.Errorf("Info message visibility: got %v, want %v", hasInfo, tt.shouldShowInfo)
+			}
+			if hasWarn != tt.shouldShowWarn {
+				t.Errorf("Warn message visibility: got %v, want %v", hasWarn, tt.shouldShowWarn)
+			}
+			if hasError != tt.shouldShowError {
+				t.Errorf("Error message visibility: got %v, want %v", hasError, tt.shouldShowError)
+			}
+
+			t.Logf("LOG_LEVEL=%s parsed to level %d (%s), output length: %d bytes",
+				tt.logLevel, parsedLevel, logging.LevelNames[parsedLevel], len(output))
+		})
+	}
+}
+
+func TestMainApplicationLogLevelIntegration(t *testing.T) {
+	tests := []struct {
+		name        string
+		logLevel    string
+		expectLevel int
+	}{
+		{"Debug level", "debug", logging.LEVEL_DEBUG},
+		{"Info level", "info", logging.LEVEL_INFO},
+		{"Warn level", "warn", logging.LEVEL_WARN},
+		{"Error level", "error", logging.LEVEL_ERROR},
+		{"Empty defaults to info", "", logging.LEVEL_INFO},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Save original environment
+			originalLogLevel := os.Getenv("LOG_LEVEL")
+			defer os.Setenv("LOG_LEVEL", originalLogLevel)
+
+			// Set test LOG_LEVEL
+			if tt.logLevel == "" {
+				os.Unsetenv("LOG_LEVEL")
+			} else {
+				os.Setenv("LOG_LEVEL", tt.logLevel)
+			}
+
+			// Create new connection (this tests main.go integration)
+			client := NewConnection()
+
+			// Set up buffer for test logging
+			var buf bytes.Buffer
+			client.Logger.SetOutput(&buf)
+
+			// Verify the logger was configured with correct level by testing behavior
+			client.Logger.Debug(&logging.LogMessage{Message: "test debug"})
+			client.Logger.Info(&logging.LogMessage{Message: "test info"})
+
+			output := buf.String()
+
+			// The main validation is that the logger respects the LOG_LEVEL setting
+			// We can see from the console output that initialization works correctly
+
+			// Verify level parsing worked correctly by checking if debug shows when expected
+			hasDebug := strings.Contains(output, "test debug")
+			shouldShowDebug := tt.expectLevel <= logging.LEVEL_DEBUG
+
+			if hasDebug != shouldShowDebug {
+				t.Errorf("Debug visibility: got %v, want %v for level %s", hasDebug, shouldShowDebug, tt.logLevel)
+			}
+
+			t.Logf("NewConnection() with LOG_LEVEL=%s created logger, output length: %d bytes",
+				tt.logLevel, len(output))
+		})
+	}
+}
+
+func TestTestHelpersLogLevelIntegration(t *testing.T) {
+	tests := []struct {
+		name        string
+		logLevel    string
+		expectLevel int
+	}{
+		{"Test with debug level", "debug", logging.LEVEL_DEBUG},
+		{"Test with info level", "info", logging.LEVEL_INFO},
+		{"Test with warn level", "warn", logging.LEVEL_WARN},
+		{"Test with error level", "error", logging.LEVEL_ERROR},
+		{"Test with no LOG_LEVEL (defaults to error)", "", logging.LEVEL_ERROR},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Save original environment
+			originalLogLevel := os.Getenv("LOG_LEVEL")
+			defer os.Setenv("LOG_LEVEL", originalLogLevel)
+
+			// Set test LOG_LEVEL
+			if tt.logLevel == "" {
+				os.Unsetenv("LOG_LEVEL")
+			} else {
+				os.Setenv("LOG_LEVEL", tt.logLevel)
+			}
+
+			// Reset test logger to force re-initialization
+			testLogger = nil
+
+			// Get test logger (this tests test_helpers.go integration)
+			var buf bytes.Buffer
+			logger := GetTestLogger()
+			logger.SetOutput(&buf)
+
+			// Test logging at different levels
+			logger.Debug(&logging.LogMessage{Message: "test debug"})
+			logger.Info(&logging.LogMessage{Message: "test info"})
+			logger.Warn(&logging.LogMessage{Message: "test warn"})
+			logger.Error(&logging.LogMessage{Message: "test error"})
+
+			output := buf.String()
+
+			// The test logger initialization works correctly as seen in console output
+			// Focus on validating the actual log level behavior
+
+			// Verify level filtering works correctly
+			hasDebug := strings.Contains(output, "test debug")
+			hasInfo := strings.Contains(output, "test info")
+			hasWarn := strings.Contains(output, "test warn")
+			hasError := strings.Contains(output, "test error")
+
+			shouldShowDebug := tt.expectLevel <= logging.LEVEL_DEBUG
+			shouldShowInfo := tt.expectLevel <= logging.LEVEL_INFO
+			shouldShowWarn := tt.expectLevel <= logging.LEVEL_WARN
+			shouldShowError := tt.expectLevel <= logging.LEVEL_ERROR
+
+			if hasDebug != shouldShowDebug {
+				t.Errorf("Debug visibility: got %v, want %v", hasDebug, shouldShowDebug)
+			}
+			if hasInfo != shouldShowInfo {
+				t.Errorf("Info visibility: got %v, want %v", hasInfo, shouldShowInfo)
+			}
+			if hasWarn != shouldShowWarn {
+				t.Errorf("Warn visibility: got %v, want %v", hasWarn, shouldShowWarn)
+			}
+			if hasError != shouldShowError {
+				t.Errorf("Error visibility: got %v, want %v", hasError, shouldShowError)
+			}
+
+			t.Logf("GetTestLogger() with LOG_LEVEL=%s, output length: %d bytes",
+				tt.logLevel, len(output))
+		})
+	}
+}
+
+func TestLogLevelCaseInsensitive(t *testing.T) {
+	testCases := []string{"DEBUG", "Info", "WARN", "Error", "debug", "info", "warn", "error"}
+
+	for _, testCase := range testCases {
+		t.Run("Case_"+testCase, func(t *testing.T) {
+			level := logging.GetLogLevel(testCase)
+			expectedLevel := logging.GetLogLevel(strings.ToLower(testCase))
+
+			if level != expectedLevel {
+				t.Errorf("GetLogLevel(%s) = %d, want %d (case insensitive)", testCase, level, expectedLevel)
+			}
+		})
+	}
+}

main.go

@@ -10,10 +10,29 @@ import (
 )
 
 func NewConnection() (b *BaseClient) {
+	// Read LOG_LEVEL environment variable
+	logLevelStr := envutil.Getenv("LOG_LEVEL", "info")
+	logLevel := logging.GetLogLevel(logLevelStr)
+
+	// Create logger and set the log level from environment
+	logger := logging.New()
+	logger.SetMinLogLevel(logLevel)
+
+	// Log the LOG_LEVEL configuration for validation
+	logger.Info(&logging.LogMessage{
+		Message: "Logger initialized with LOG_LEVEL configuration",
+		Pairs: map[string]interface{}{
+			"LOG_LEVEL_env_var": logLevelStr,
+			"parsed_log_level":  logLevel,
+			"level_name":        logging.LevelNames[logLevel],
+			"default_min_level": logging.LEVEL_INFO,
+		},
+	})
+
 	b = &BaseClient{
 		endpoint:       envutil.Getenv("GRAPHQL_ENDPOINT", "https://api.github.com/graphql"),
 		responseType:   envutil.Getenv("GRAPHQL_OUTPUT", "string"),
-		Logger:         logging.New(),
+		Logger:         logger,
 		cache:          cache.New(time.Duration(envutil.GetInt("GRAPHQL_CACHE_TTL", 5)) * time.Second),
 		cache_global:   envutil.GetBool("GRAPHQL_CACHE_ENABLED", false),
 		retries_enable: envutil.GetBool("GRAPHQL_RETRIES_ENABLE", false),
@@ -25,7 +44,8 @@ func NewConnection() (b *BaseClient) {
 		Message: "Created new GraphQL client connection",
 		Pairs: map[string]interface{}{
 			"values": b,
-		}})
+		},
+	})
 	return b
 }
 

structs.go

@@ -24,7 +24,7 @@ type BaseClient struct {
 type Query struct {
 	Variables map[string]interface{} `json:"variables,omitempty"`
 	Query     string                 `json:"query,omitempty"`
-	JsonQuery []byte                 `json:"jsonQuery,omitempty"`
+	JsonQuery []byte                 `json:"-"` // Exclude from JSON serialization to prevent nested encoding
 }
 
 type QueryExecutor struct {

test_helpers.go

@@ -1,6 +1,7 @@
 package gql
 
 import (
+	"os"
 	"sync"
 	"time"
 
@@ -26,7 +27,25 @@ func GetTestCache() *cache.Cache {
 func GetTestLogger() *logging.Logger {
 	if testLogger == nil {
 		testLogger = logging.New()
-		testLogger.SetMinLogLevel(logging.LEVEL_ERROR)
+
+		// Check if LOG_LEVEL is set for tests, otherwise use LEVEL_ERROR
+		logLevelStr := "error" // Default for tests
+		if envLogLevel := os.Getenv("LOG_LEVEL"); envLogLevel != "" {
+			logLevelStr = envLogLevel
+		}
+		logLevel := logging.GetLogLevel(logLevelStr)
+		testLogger.SetMinLogLevel(logLevel)
+
+		// Log test logger configuration for validation
+		testLogger.Info(&logging.LogMessage{
+			Message: "Test logger initialized",
+			Pairs: map[string]interface{}{
+				"LOG_LEVEL_env_var":   os.Getenv("LOG_LEVEL"),
+				"effective_log_level": logLevelStr,
+				"parsed_log_level":    logLevel,
+				"level_name":          logging.LevelNames[logLevel],
+			},
+		})
 	}
 	return testLogger
 }