Refactoring of BLF module

Implement append mode
Write a temporary header in case logging is not stopped gracefully
Move ZLIB compression level to constructor, default to ZLIB default
Improve unit testing
Various refactoring to improve readability and slight performance improvements

Author: christiansandberg

can/io/blf.py

@@ -108,6 +108,16 @@ def sort_messages(messages):
 )
 
 
+TEST_MESSAGES_CAN_FD = sort_messages(
+    [
+        Message(is_fd=True, data=range(64)),
+        Message(is_fd=True, data=range(8)),
+        Message(is_fd=True, bitrate_switch=True),
+        Message(is_fd=True, error_state_indicator=True),
+    ]
+)
+
+
 TEST_MESSAGES_REMOTE_FRAMES = sort_messages(
     [
         Message(

test/data/example_data.py

@@ -90,7 +90,9 @@ def test_filetype_to_instance(extension, klass):
             try:
                 if extension == ".blf":
                     delete = False
-                    file_handler = open(join(dirname(__file__), "data/logfile.blf"))
+                    file_handler = open(
+                        join(dirname(__file__), "data", "test_CanMessage.blf")
+                    )
                 else:
                     delete = True
                     file_handler = tempfile.NamedTemporaryFile(

test/data/logfile.blf

@@ -27,6 +27,7 @@
     TEST_MESSAGES_BASE,
     TEST_MESSAGES_REMOTE_FRAMES,
     TEST_MESSAGES_ERROR_FRAMES,
+    TEST_MESSAGES_CAN_FD,
     TEST_COMMENTS,
     sort_messages,
 )
@@ -89,13 +90,13 @@ def _setup_instance_helper(
                                          ignored, if *preserves_channel* is True
         """
         # get all test messages
-        self.original_messages = TEST_MESSAGES_BASE
+        self.original_messages = list(TEST_MESSAGES_BASE)
         if check_remote_frames:
             self.original_messages += TEST_MESSAGES_REMOTE_FRAMES
         if check_error_frames:
             self.original_messages += TEST_MESSAGES_ERROR_FRAMES
         if check_fd:
-            self.original_messages += []  # TODO: add TEST_MESSAGES_CAN_FD
+            self.original_messages += TEST_MESSAGES_CAN_FD
 
         # sort them so that for example ASCWriter does not "fix" any messages with timestamp 0.0
         self.original_messages = sort_messages(self.original_messages)
@@ -345,41 +346,101 @@ def _setup_instance(self):
 
 
 class TestBlfFileFormat(ReaderWriterTest):
-    """Tests can.BLFWriter and can.BLFReader"""
+    """Tests can.BLFWriter and can.BLFReader.
+    
+    Uses log files created by Toby Lorenz:
+    https://bitbucket.org/tobylorenz/vector_blf/src/master/src/Vector/BLF/tests/unittests/events_from_binlog/
+    """
 
     def _setup_instance(self):
         super()._setup_instance_helper(
             can.BLFWriter,
             can.BLFReader,
             binary_file=True,
-            check_fd=False,
+            check_fd=True,
             check_comments=False,
+            test_append=True,
             allowed_timestamp_delta=1.0e-6,
             preserves_channel=False,
             adds_default_channel=0,
         )
 
-    def test_read_known_file(self):
-        logfile = os.path.join(os.path.dirname(__file__), "data", "logfile.blf")
+    def _read_log_file(self, filename):
+        logfile = os.path.join(os.path.dirname(__file__), "data", filename)
         with can.BLFReader(logfile) as reader:
-            messages = list(reader)
-
-        expected = [
-            can.Message(
-                timestamp=1.0,
-                is_extended_id=False,
-                arbitration_id=0x64,
-                data=[0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8],
-            ),
-            can.Message(
-                timestamp=73.0,
-                is_extended_id=True,
-                arbitration_id=0x1FFFFFFF,
-                is_error_frame=True,
-            ),
-        ]
-
-        self.assertMessagesEqual(messages, expected)
+            return list(reader)
+
+    def test_can_message(self):
+        expected = can.Message(
+            timestamp=2459565876.494607,
+            arbitration_id=0x4444444,
+            is_extended_id=False,
+            channel=0x1110,
+            dlc=0x33,
+            data=[0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC],
+        )
+        actual = self._read_log_file("test_CanMessage.blf")
+        self.assertMessagesEqual(actual, [expected] * 2)
+        self.assertEqual(actual[0].channel, expected.channel)
+
+    def test_can_message_2(self):
+        expected = can.Message(
+            timestamp=2459565876.494607,
+            arbitration_id=0x4444444,
+            is_extended_id=False,
+            channel=0x1110,
+            dlc=0x33,
+            data=[0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC],
+        )
+        actual = self._read_log_file("test_CanMessage2.blf")
+        self.assertMessagesEqual(actual, [expected] * 2)
+        self.assertEqual(actual[0].channel, expected.channel)
+
+    def test_can_fd_message(self):
+        expected = can.Message(
+            timestamp=2459565876.494607,
+            arbitration_id=0x4444444,
+            is_extended_id=False,
+            channel=0x1110,
+            dlc=64,
+            is_fd=True,
+            bitrate_switch=True,
+            error_state_indicator=True,
+            data=range(64),
+        )
+        actual = self._read_log_file("test_CanFdMessage.blf")
+        self.assertMessagesEqual(actual, [expected] * 2)
+        self.assertEqual(actual[0].channel, expected.channel)
+
+    def test_can_fd_message_64(self):
+        expected = can.Message(
+            timestamp=2459565876.494607,
+            arbitration_id=0x15555555,
+            is_extended_id=False,
+            is_remote_frame=True,
+            channel=0x10,
+            dlc=64,
+            is_fd=True,
+            bitrate_switch=True,
+            error_state_indicator=True,
+        )
+        actual = self._read_log_file("test_CanFdMessage64.blf")
+        self.assertMessagesEqual(actual, [expected] * 2)
+        self.assertEqual(actual[0].channel, expected.channel)
+
+    def test_can_error_frame_ext(self):
+        expected = can.Message(
+            timestamp=2459565876.494607,
+            is_error_frame=True,
+            arbitration_id=0x19999999,
+            is_extended_id=True,
+            channel=0x1110,
+            dlc=0x66,
+            data=[0xCC, 0xDD, 0xEE, 0xFF, 0x11, 0x22, 0x33, 0x44],
+        )
+        actual = self._read_log_file("test_CanErrorFrameExt.blf")
+        self.assertMessagesEqual(actual, [expected] * 2)
+        self.assertEqual(actual[0].channel, expected.channel)
 
 
 class TestCanutilsFileFormat(ReaderWriterTest):