Fix for low line lenghts on fancy exporter

See https://github.com/jrnl-org/jrnl/pull/1219

tests/test_export.py

@@ -0,0 +1,28 @@
+from jrnl.exception import JrnlError
+from jrnl.plugins.fancy_exporter import check_provided_linewrap_viability
+
+import pytest
+
+
+@pytest.fixture()
+def datestr():
+    yield "2020-10-20 16:59"
+
+
+def build_card_header(datestr):
+    top_left_corner = "┎─╮"
+    content = top_left_corner + datestr
+    return content
+
+
+class TestFancy:
+    def test_too_small_linewrap(self, datestr):
+
+        journal = "test_journal"
+        content = build_card_header(datestr)
+
+        total_linewrap = 12
+
+        with pytest.raises(JrnlError) as e:
+            check_provided_linewrap_viability(total_linewrap, [content], journal)
+        assert e.value.error_type == "LineWrapTooSmallForDateFormat"