test(platform): Unit test covering checksum generation with files > 8MB

Author: helmut-hoffer-von-ankershoffen

tests/aignostics/platform/utils_test.py

@@ -1,11 +1,13 @@
 """Tests for the platform utility functions."""
 
 import math
+import tempfile
+from pathlib import Path
 
 import pytest
 
 from aignostics.platform import mime_type_to_file_ending
-from aignostics.platform._utils import convert_to_json_serializable
+from aignostics.platform._utils import calculate_file_crc32c, convert_to_json_serializable
 
 
 class TestConvertToJsonSerializable:
@@ -239,3 +241,105 @@ def test_unknown_mime_type_raises_error(record_property) -> None:
         record_property("tested-item-id", "SPEC-PLATFORM-SERVICE")
         with pytest.raises(ValueError, match="Unknown mime type: application/unknown"):
             mime_type_to_file_ending("application/unknown")
+
+
+class TestCalculateFileCrc32c:
+    """Tests for the calculate_file_crc32c function."""
+
+    @pytest.mark.unit
+    @staticmethod
+    def test_calculate_crc32c_small_file(record_property) -> None:
+        """Test CRC32C calculation for a small file.
+
+        This test verifies that the calculate_file_crc32c function correctly
+        calculates the CRC32C checksum for a small file that fits in a single chunk.
+        """
+        record_property("tested-item-id", "SPEC-PLATFORM-SERVICE")
+        with tempfile.NamedTemporaryFile(mode="wb", delete=False) as temp_file:
+            temp_path = Path(temp_file.name)
+            temp_file.write(b"Hello, World!")
+
+        try:
+            checksum = calculate_file_crc32c(temp_path)
+            # Verify it returns a base64-encoded string
+            assert isinstance(checksum, str)
+            assert len(checksum) > 0
+            # The checksum for "Hello, World!" should be consistent
+            assert checksum == "TVUQaA=="
+        finally:
+            temp_path.unlink()
+
+    @pytest.mark.unit
+    @staticmethod
+    def test_calculate_crc32c_large_file(record_property) -> None:
+        """Test CRC32C calculation for a large file with multiple chunks.
+
+        This test verifies that the calculate_file_crc32c function correctly
+        calculates the CRC32C checksum for a file larger than 8MB, ensuring
+        the continue statement (line 187) is executed multiple times.
+        """
+        record_property("tested-item-id", "SPEC-PLATFORM-SERVICE")
+        # Create a file larger than EIGHT_MB (8,388,608 bytes)
+        # Use 10MB to ensure multiple chunks
+        file_size = 10 * 1024 * 1024  # 10 MB
+        chunk_data = b"A" * (1024 * 1024)  # 1 MB chunks
+
+        with tempfile.NamedTemporaryFile(mode="wb", delete=False) as temp_file:
+            temp_path = Path(temp_file.name)
+            for _ in range(10):  # Write 10 chunks of 1MB each
+                temp_file.write(chunk_data)
+
+        try:
+            checksum = calculate_file_crc32c(temp_path)
+            # Verify it returns a base64-encoded string
+            assert isinstance(checksum, str)
+            assert len(checksum) > 0
+            # Verify file size is as expected
+            assert temp_path.stat().st_size == file_size
+        finally:
+            temp_path.unlink()
+
+    @pytest.mark.unit
+    @staticmethod
+    def test_calculate_crc32c_empty_file(record_property) -> None:
+        """Test CRC32C calculation for an empty file.
+
+        This test verifies that the calculate_file_crc32c function correctly
+        handles empty files.
+        """
+        record_property("tested-item-id", "SPEC-PLATFORM-SERVICE")
+        with tempfile.NamedTemporaryFile(mode="wb", delete=False) as temp_file:
+            temp_path = Path(temp_file.name)
+            # Don't write anything, leave file empty
+
+        try:
+            checksum = calculate_file_crc32c(temp_path)
+            # Verify it returns a base64-encoded string
+            assert isinstance(checksum, str)
+            assert len(checksum) > 0
+            # Empty file CRC32C checksum
+            assert checksum == "AAAAAA=="
+        finally:
+            temp_path.unlink()
+
+    @pytest.mark.unit
+    @staticmethod
+    def test_calculate_crc32c_deterministic(record_property) -> None:
+        """Test that CRC32C calculation is deterministic.
+
+        This test verifies that calculating the checksum multiple times for
+        the same file produces the same result.
+        """
+        record_property("tested-item-id", "SPEC-PLATFORM-SERVICE")
+        test_data = b"Test data for deterministic checksum verification"
+
+        with tempfile.NamedTemporaryFile(mode="wb", delete=False) as temp_file:
+            temp_path = Path(temp_file.name)
+            temp_file.write(test_data)
+
+        try:
+            checksum1 = calculate_file_crc32c(temp_path)
+            checksum2 = calculate_file_crc32c(temp_path)
+            assert checksum1 == checksum2
+        finally:
+            temp_path.unlink()