test: add performance benchmarks for compression

- Test compression overhead is under 20ms threshold
- Test at multiple content sizes (512, 1024, 5000, 10000 bytes)
- Test compression ratio for realistic code content
- Ensure performance requirements are met

Author: Pdzly

backend/tests/performance/test_compression_performance.py

@@ -0,0 +1,88 @@
+import time
+import pytest
+from app.utils.compression import compress_content, decompress_content
+
+
+class TestCompressionPerformance:
+    """Performance tests for compression functionality."""
+
+    @pytest.mark.parametrize("size", [512, 1024, 5000, 10000])
+    def test_compression_performance_overhead(self, size):
+        """Test that compression overhead is under 20ms threshold."""
+        # Create content of specified size
+        content = "x" * size
+
+        # Measure compression time
+        start_compress = time.perf_counter()
+        compressed, original_size = compress_content(content)
+        end_compress = time.perf_counter()
+        compress_time_ms = (end_compress - start_compress) * 1000
+
+        # Measure decompression time
+        start_decompress = time.perf_counter()
+        decompressed = decompress_content(compressed)
+        end_decompress = time.perf_counter()
+        decompress_time_ms = (end_decompress - start_decompress) * 1000
+
+        # Calculate total overhead
+        total_overhead_ms = compress_time_ms + decompress_time_ms
+
+        # Print results for visibility
+        print(f"\nSize {size}: compress={compress_time_ms:.3f}ms, decompress={decompress_time_ms:.3f}ms, total={total_overhead_ms:.3f}ms")
+
+        # Verify decompression works
+        assert decompressed == content
+
+        # Assert total overhead is under 20ms
+        assert total_overhead_ms < 20, f"Compression overhead {total_overhead_ms:.3f}ms exceeds 20ms threshold"
+
+    def test_compression_ratio_realistic_code(self):
+        """Test compression ratio for realistic code content."""
+        # Create realistic code content - Python function repeated 20 times
+        code_snippet = """
+def calculate_fibonacci(n):
+    '''Calculate the nth Fibonacci number.'''
+    if n <= 1:
+        return n
+    a, b = 0, 1
+    for _ in range(2, n + 1):
+        a, b = b, a + b
+    return b
+
+class DataProcessor:
+    def __init__(self, data):
+        self.data = data
+        self.processed = False
+
+    def process(self):
+        '''Process the data.'''
+        result = []
+        for item in self.data:
+            if isinstance(item, int):
+                result.append(item * 2)
+            else:
+                result.append(str(item).upper())
+        self.processed = True
+        return result
+"""
+        realistic_content = code_snippet * 20
+        original_size = len(realistic_content)
+
+        # Compress the content
+        compressed, _ = compress_content(realistic_content)
+        compressed_size = len(compressed)
+
+        # Calculate compression ratio
+        compression_ratio = compressed_size / original_size
+
+        # Print results
+        print(f"\nOriginal size: {original_size} bytes")
+        print(f"Compressed size: {compressed_size} bytes")
+        print(f"Compression ratio: {compression_ratio:.3f}")
+
+        # Verify decompression works
+        decompressed = decompress_content(compressed)
+        assert decompressed == realistic_content
+
+        # Assert compression ratio is under 0.4 (40%)
+        assert compression_ratio < 0.4, f"Compression ratio {compression_ratio:.3f} exceeds 0.4 threshold"