enforce positive initial linewrap

Check column widths

update gitignore

throw error when linewrap too small

simply check for large enough linewrap value

tests/test_export.py

@@ -0,0 +1,39 @@
+from jrnl.exception import JrnlError
+from jrnl.plugins.fancy_exporter import FancyExporter
+
+
+import pytest
+
+
+@pytest.fixture()
+def datestr():
+
+    yield "2020-10-20 16:59"
+
+
+from textwrap import TextWrapper
+
+
+def provide_date_wrapper(initial_linewrap):
+    wrapper = TextWrapper(
+        width=initial_linewrap, initial_indent=" ", subsequent_indent=" "
+    )
+    return wrapper
+
+
+def build_card_header(datestr):
+    top_left_corner = "┎─╮"
+    content = top_left_corner + datestr
+    return content
+
+
+class TestFancy:
+    def test_too_small_linewrap(self, datestr):
+
+        content = build_card_header(datestr)
+
+        total_linewrap = 12
+
+        with pytest.raises(JrnlError) as e:
+            FancyExporter.check_linewrap(total_linewrap, [content])
+        assert e.value.error_type == "LineWrapTooSmallForDateFormat"