fix: correctly print multi-line errors

craft_cli/messages.py

@@ -710,7 +710,7 @@ def ended_ok(self) -> None:
         """Finish the messaging system gracefully."""
         self._stop()
 
-    def _report_error(self, error: errors.CraftError) -> None:
+    def _report_error(self, error: errors.CraftError) -> None:  # noqa: PLR0912 (too many branches)
         """Report the different message lines from a CraftError."""
         if self._mode in (EmitterMode.QUIET, EmitterMode.BRIEF, EmitterMode.VERBOSE):
             use_timestamp = False
@@ -719,8 +719,10 @@ def _report_error(self, error: errors.CraftError) -> None:
             use_timestamp = True
             full_stream = sys.stderr
 
-        # the initial message
-        self._printer.show(sys.stderr, str(error), use_timestamp=use_timestamp, end_line=True)
+        # the initial message. Print every line individually to correctly clear
+        # previous lines, if necessary.
+        for line in str(error).splitlines():
+            self._printer.show(sys.stderr, line, use_timestamp=use_timestamp, end_line=True)
 
         if isinstance(error, errors.CraftCommandError):
             stderr = error.stderr

examples.py

@@ -513,6 +513,15 @@ def example_30():
         time.sleep(0.001)
 
 
+def example_31():
+    """Multiline error message."""
+    emit.progress("Setting up computer for build...")
+    time.sleep(1)
+    emit.progress("A long progress message")
+    time.sleep(6)
+    raise CraftError("Error 1\nError 2")
+
+
 # -- end of test cases
 
 if len(sys.argv) < 2:

tests/integration/test_messages_integration.py

@@ -1010,6 +1010,23 @@ def test_error_unexpected_debugish(capsys, mode):
     assert_outputs(capsys, emit, expected_err=expected, expected_log=expected)
 
 
+@pytest.mark.parametrize("output_is_terminal", [True])
+def test_error_multiline_brief(capsys):
+    emit = Emitter()
+    emit.init(EmitterMode.BRIEF, "testapp", GREETING)
+    emit.progress("A very long message detailing the current task.")
+    error = CraftError("Error line 1.\nError line 2.", logpath_report=False)
+    emit.error(error)
+
+    expected = [
+        Line("A very long message detailing the current task.", permanent=False),
+        # The error message is split on two separate lines.
+        Line("Error line 1.", permanent=True),
+        Line("Error line 2.", permanent=True),
+    ]
+    assert_outputs(capsys, emit, expected_err=expected, expected_log=expected)
+
+
 @pytest.mark.parametrize(
     "mode",
     [