feat(tools): fw_info/fw_pack 镜像解析重打包（CRC32验证+字节级往返），112 测试全绿

tests/test_fw.py

@@ -0,0 +1,64 @@
+"""固件工具测试 — 以原始镜像为黄金样本（app/ 只读）。"""
+import zlib
+from pathlib import Path
+
+import pytest
+
+from tools import fw
+
+SAMPLE = Path(__file__).parent.parent / "app" / "firmware-PP_da14585_4.2_CH.img"
+
+
+@pytest.fixture
+def sample():
+    return SAMPLE.read_bytes()
+
+
+class TestParse:
+    def test_header_fields(self, sample):
+        info = fw.parse_image(sample)
+        assert info["magic"] == 0x7051  # 'pQ'
+        assert info["flags"] == 0x01AA
+        assert info["body_size"] == len(sample) - 64
+        assert info["crc_stored"] == zlib.crc32(sample[64:]) & 0xFFFFFFFF
+
+    def test_crc_valid(self, sample):
+        assert fw.parse_image(sample)["crc_valid"] is True
+
+    def test_vector_table(self, sample):
+        info = fw.parse_image(sample)
+        assert info["initial_sp"] == 0x07FD2B58
+        assert info["reset_handler"] == 0x07FC0525
+        assert info["load_base"] == 0x07FC0000
+
+    def test_bad_magic_rejected(self):
+        with pytest.raises(ValueError):
+            fw.parse_image(b"\x00" * 128)
+
+    def test_bad_crc_reported(self, sample):
+        corrupted = bytearray(sample)
+        corrupted[100] ^= 0xFF
+        assert fw.parse_image(bytes(corrupted))["crc_valid"] is False
+
+
+class TestPack:
+    def test_repack_roundtrip_byte_identical(self, sample):
+        """解包→重打包 == 原文件（字节级）"""
+        body = fw.unpack_body(sample)
+        assert fw.pack_image(body, flags=0x01AA) == sample
+
+    def test_pack_computes_crc(self):
+        body = b"\x58\x2b\xfd\x07" + b"\x00" * 100
+        img = fw.pack_image(body)
+        info = fw.parse_image(img)
+        assert info["crc_valid"] is True
+        assert info["body_size"] == len(body)
+
+    def test_patch_and_repack(self, sample):
+        """修改体→重打包→CRC 更新且可解析"""
+        body = bytearray(fw.unpack_body(sample))
+        body[0x1000] ^= 0xAA
+        img = fw.pack_image(bytes(body))
+        info = fw.parse_image(img)
+        assert info["crc_valid"] is True
+        assert img != sample