More graceful handling of low linewrap values

features/format.feature

@@ -297,6 +297,22 @@ Feature: Custom formats
         | basic_folder    |
         | basic_dayone    |
 
+
+
+    Scenario Outline: Export fancy with small linewrap
+        Given we use the config "<config>.yaml"
+        And we use the password "test" if prompted
+        When we run "jrnl --config-override linewrap 35 --format fancy -3"
+        Then we should get no error
+        And the output should be 35 columns wide
+
+        Examples: configs
+        | config          |
+        | basic_onefile   |
+        | basic_encrypted |
+        | basic_folder    |
+        | basic_dayone    |
+
     @todo
     Scenario Outline: Exporting fancy
         # Needs better emoji support

features/steps/export_steps.py

@@ -12,6 +12,14 @@
 from behave import then
 
 
+@then("the output should be {width:d} columns wide")
+def check_output_width(context, width):
+    out = context.stdout_capture.getvalue()
+    out_lines = out.splitlines()
+    for line in out_lines:
+        assert len(line) <= width
+
+
 @then("the output should be parsable as json")
 def check_output_json(context):
     out = context.stdout_capture.getvalue()

jrnl/exception.py

@@ -30,7 +30,15 @@ def _get_error_message(self, **kwargs):
 
                 Removing this file will allow jrnl to save its configuration.
             """
-            )
+            ),
+            "LineWrapTooSmallForDateFormat": textwrap.dedent(
+                """
+                The provided linewrap value of {config_linewrap} is too small by {columns} columns
+                to display the timestamps in the configured time format for journal {journal}.
+
+                You can avoid this error by specifying a linewrap value that is larger by at least {columns} in the configuration file or by using --config-override at the command line 
+                """
+            ),
         }
 
         return error_messages[self.error_type].format(**kwargs)

jrnl/plugins/fancy_exporter.py

@@ -3,6 +3,7 @@
 # Copyright (C) 2012-2021 jrnl contributors
 # License: https://www.gnu.org/licenses/gpl-3.0.html
 
+from jrnl.exception import JrnlError
 from textwrap import TextWrapper
 
 from .text_exporter import TextExporter
@@ -14,12 +15,14 @@ class FancyExporter(TextExporter):
     names = ["fancy", "boxed"]
     extension = "txt"
 
+    # Top border of the card
     border_a = "┎"
     border_b = "─"
     border_c = "╮"
     border_d = "╘"
     border_e = "═"
     border_f = "╕"
+
     border_g = "┃"
     border_h = "│"
     border_i = "┠"
@@ -33,16 +36,19 @@ def export_entry(cls, entry):
         """Returns a fancy unicode representation of a single entry."""
         date_str = entry.date.strftime(entry.journal.config["timeformat"])
         linewrap = entry.journal.config["linewrap"] or 78
-        initial_linewrap = linewrap - len(date_str) - 2
+        initial_linewrap = max((1, linewrap - len(date_str) - 2))
         body_linewrap = linewrap - 2
         card = [
             cls.border_a + cls.border_b * (initial_linewrap) + cls.border_c + date_str
         ]
+        check_provided_linewrap_viability(linewrap, card, entry.journal)
+
         w = TextWrapper(
             width=initial_linewrap,
             initial_indent=cls.border_g + " ",
             subsequent_indent=cls.border_g + " ",
         )
+
         title_lines = w.wrap(entry.title)
         card.append(
             title_lines[0].ljust(initial_linewrap + 1)
@@ -74,3 +80,16 @@ def export_entry(cls, entry):
     def export_journal(cls, journal):
         """Returns a unicode representation of an entire journal."""
         return "\n".join(cls.export_entry(entry) for entry in journal)
+
+
+def check_provided_linewrap_viability(linewrap, card, journal):
+    if len(card[0]) > linewrap:
+        width_violation = len(card[0]) - linewrap
+        raise JrnlError(
+            "LineWrapTooSmallForDateFormat",
+            config_linewrap=linewrap,
+            columns=width_violation,
+            journal=journal,
+        )
+    else:
+        pass

tests/test_export.py

@@ -0,0 +1,39 @@
+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"
+
+
+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):
+
+        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"