tests: cpatch: added

Add basic patching tests for the `cpatch` module.

Signed-off-by: Jordan Yates <jordan@embeint.com>

Author: JordanYates

tests/test_cpatch.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+
+import os
+import subprocess
+import sys
+
+import pytest
+
+from infuse_iot.cpatch import ValidationError, cpatch
+
+assert "TOXTEMPDIR" in os.environ, "you must run these tests using tox"
+
+
+def apply_generated_patch(tmp_path, original: bytes, expected: bytes) -> bytes:
+    original_file = tmp_path / "original.bin"
+    new_file = tmp_path / "new.bin"
+    patch_file = tmp_path / "update.cpatch"
+    output_file = tmp_path / "output.bin"
+
+    original_file.write_bytes(original)
+    new_file.write_bytes(expected)
+
+    subprocess.run(
+        [sys.executable, "-m", "infuse_iot.cpatch", "generate", original_file, new_file, patch_file],
+        check=True,
+        stdout=subprocess.DEVNULL,
+    )
+    subprocess.run(
+        [sys.executable, "-m", "infuse_iot.cpatch", "patch", original_file, patch_file, output_file],
+        check=True,
+        stdout=subprocess.DEVNULL,
+    )
+
+    return output_file.read_bytes()
+
+
+@pytest.mark.parametrize(
+    ("original", "expected"),
+    [
+        pytest.param(bytes(range(64)), bytes(range(64)), id="unchanged"),
+        pytest.param(bytes(range(64)), bytes(range(16)) + b"HELLO" + bytes(range(21, 64)), id="rewrite"),
+        pytest.param(bytes(range(64)), bytes(range(64)) + b"TAIL", id="append"),
+        pytest.param(bytes(range(64)), bytes(range(16)) + bytes(range(24, 64)), id="delete"),
+        pytest.param(b"abcdefgh" * 8 + b"ijklmnop" * 8, b"ijklmnop" * 8 + b"abcdefgh" * 8, id="reuse"),
+    ],
+)
+def test_cli_generates_patch_that_reconstructs_expected_output(tmp_path, original, expected):
+    assert apply_generated_patch(tmp_path, original, expected) == expected
+
+
+def test_patch_rejects_wrong_original_contents():
+    original = bytes(range(64))
+    expected = bytes(range(16)) + b"HELLO" + bytes(range(21, 64))
+    patch = cpatch.generate(original, expected, verbose=False)
+
+    with pytest.raises(ValidationError, match="Original file CRC"):
+        cpatch.patch(bytes(reversed(original)), patch)
+
+
+def test_validation_patch_reconstructs_original():
+    original = bytes(range(256)) * 5
+    patch = cpatch.validation(original, invalid_length=False, invalid_crc=False)
+
+    assert cpatch.patch(original, patch) == original
+
+
+@pytest.mark.parametrize(
+    ("invalid_length", "invalid_crc", "message"),
+    [
+        pytest.param(True, False, "length does not match", id="invalid-length"),
+        pytest.param(False, True, "CRC does not match", id="invalid-crc"),
+    ],
+)
+def test_validation_patch_can_generate_invalid_output_metadata(invalid_length, invalid_crc, message):
+    original = bytes(range(256)) * 5
+    patch = cpatch.validation(original, invalid_length=invalid_length, invalid_crc=invalid_crc)
+
+    with pytest.raises(ValidationError, match=message):
+        cpatch.patch(original, patch)