Add unit tests for the 'cabfile' module.

spotfire/test/__main__.py

@@ -12,7 +12,9 @@
 
 from spotfire.test import utils
 
-TEST_MODULES = ['spotfire.test.test_sbdf', 'spotfire.test.test_data_function']
+TEST_MODULES = ['spotfire.test.test_cabfile',
+                'spotfire.test.test_data_function',
+                'spotfire.test.test_sbdf']
 
 
 # noinspection PyUnusedLocal

spotfire/test/test_cabfile.py

@@ -0,0 +1,90 @@
+"""Tests for verifying the creation of cabinet files."""
+
+import platform
+import tempfile
+import unittest
+
+from spotfire import cabfile
+from spotfire.test import utils
+
+
+class CabFileTest(unittest.TestCase):
+    """Unit tests for public functions in 'spotfire.cabfile' module."""
+    def _platform_requirement(self):
+        """Correctly manage skipping tests on non-Windows platforms."""
+        if platform.system() != "Windows":
+            self.skipTest("Cabinet files not supported on non-Win32 platforms")
+
+    def test_write(self):
+        """Verify the ``write`` method."""
+        self._platform_requirement()
+        with tempfile.TemporaryDirectory() as tmpdir:
+            filename = f"{tmpdir}/qbf.txt"
+            with open(filename, "w", encoding="utf-8") as file:
+                file.write("The quick brown fox jumps over the lazy dog.\n")
+
+            with cabfile.CabFile(f"{tmpdir}/write1.cab") as cab:
+                cab.write(filename)
+            self._assert_cabfile_equals(f"{tmpdir}/write1.cab", utils.get_test_data_file("cabfile/qbf.cab"))
+
+            with cabfile.CabFile(f"{tmpdir}/write2.cab") as cab:
+                cab.write(filename, "quick.txt")
+            self._assert_cabfile_equals(f"{tmpdir}/write2.cab", utils.get_test_data_file("cabfile/qbf-quick.cab"))
+
+            with cabfile.CabFile(f"{tmpdir}/write3.cab") as cab:
+                cab.write(filename, r"qbf\quick.txt")
+            self._assert_cabfile_equals(f"{tmpdir}/write3.cab", utils.get_test_data_file("cabfile/qbf-subdir.cab"))
+
+            with self.assertRaises(ValueError):
+                # This should raise an error, since `cab` (creating 'write3.cab') is closed.
+                cab.write(filename, "nope.txt")
+
+    def test_writestr(self):
+        """Verify the ``writestr`` method."""
+        self._platform_requirement()
+        with tempfile.TemporaryDirectory() as tmpdir:
+            with cabfile.CabFile(f"{tmpdir}/writestr.cab") as cab:
+                cab.writestr("qbf.txt", b"The quick brown fox jumps over the lazy dog.\r\n")
+            self._assert_cabfile_equals(f"{tmpdir}/writestr.cab", utils.get_test_data_file("cabfile/qbf.cab"))
+
+            with self.assertRaises(ValueError):
+                cab.writestr("nope.txt",
+                             b"This should raise an error, since `cab` (creating 'writestr.cab') is closed.")
+
+    def test_platform_exceptions(self):
+        """Verify non-Windows systems raise an exception."""
+        if platform.system() == "Windows":
+            self.skipTest("Not testing non-Windows behavior on Windows")
+        else:
+            with self.assertRaises(OSError):
+                with tempfile.TemporaryDirectory() as tmpdir:
+                    cabfile.CabFile(f"{tmpdir}/exception.cab")
+
+    def _assert_cabfile_equals(self, first, second):
+        """Test that two cabinet files are equivalent, except for timestamps."""
+        with open(first, "rb") as first_file:
+            first_bytes = self._sanitize_cabfile(first_file.read())
+        with open(second, "rb") as second_file:
+            second_bytes = self._sanitize_cabfile(second_file.read())
+        self.assertEqual(first_bytes, second_bytes)
+
+    def _sanitize_cabfile(self, cab_bytes):
+        """Remove timestamps from the contents of an in-memory cabinet file."""
+        # Format information at https://learn.microsoft.com/en-us/previous-versions/bb417343(v=msdn.10)
+        barr = bytearray(cab_bytes)
+
+        # The 4-byte offset to the first CFFILE record is at offset 0x10
+        cffile_offset = self._little_endian_uint(barr[16:20])
+
+        # Set the date and time members of the first CFFILE record to known values
+        barr[cffile_offset + 10 : cffile_offset + 14] = b'\x0b\xad\xbe\xef'
+
+        return barr
+
+    @staticmethod
+    def _little_endian_uint(le_bytes):
+        val = 0
+        for byte in reversed(le_bytes):
+            val <<= 8
+            val |= byte
+        return val