Raise error when writing channel data that is not 1d (#207)

nptdms/test/writer/test_tdms_segment.py

@@ -8,7 +8,7 @@
     OrderedDict = dict
 import numpy as np
 
-from nptdms.writer import TdmsSegment, read_properties_dict
+from nptdms.writer import ChannelObject, TdmsSegment, read_properties_dict
 from nptdms.types import *
 
 
@@ -198,6 +198,20 @@ def test_error_raised_when_cannot_convert_property_value():
         read_properties_dict(properties)
 
 
+@pytest.mark.parametrize(
+    "data",
+    [
+        np.array(0.0, dtype=np.dtype('float32')),
+        np.zeros((2, 2), dtype=np.dtype('float32')),
+        np.zeros((2, 2, 2), dtype=np.dtype('float32')),
+    ]
+)
+def test_channel_with_invalid_data(data):
+    with pytest.raises(ValueError) as exc_info:
+        _ = ChannelObject("Group", "Channel", data, {})
+    assert str(exc_info.value) == "Channel data must be a 1d array"
+
+
 def _assert_sequence_equal(values, expected_values):
     position = 1
     expected_values = iter(expected_values)

nptdms/writer.py

@@ -229,6 +229,8 @@ def __init__(self, group, channel, data, properties=None):
         self.group = group
         self.channel = channel
         self.data = _to_np_array(data)
+        if self.data.ndim != 1:
+            raise ValueError("Channel data must be a 1d array")
         self.properties = properties
 
     @property