Handle wrapping when indentation exhausts the available width

devtools/prettier.py

@@ -218,7 +218,7 @@ def _str_lines(self, lines: Iterable[str | bytes], indent_current: int, indent_n
         self._stream.write(indent_current * self._c + ')')
 
     def _wrap_lines(self, s: str | bytes, indent_new: int) -> Generator[str | bytes, None, None]:
-        width = self._width - indent_new - 3
+        width = max(1, self._width - indent_new - 3)
         for line in s.splitlines(True):
             start = 0
             for pos in range(width, len(line), width):
@@ -285,13 +285,14 @@ def _format_raw(self, _: Any, value_repr: str, indent_current: int, indent_new:
         lines = value_repr.splitlines(True)
         if len(lines) > 1 or (len(value_repr) + indent_current) >= self._width:
             self._stream.write('(\n')
-            wrap_at = self._width - indent_new
+            wrap_at = max(1, self._width - indent_new)
             prefix = indent_new * self._c
 
             from textwrap import wrap
 
             for line in lines:
-                sub_lines = wrap(line, wrap_at)
+                # At width one, whitespace must occupy its own line instead of being dropped by textwrap.
+                sub_lines = line.rstrip('\r\n') if wrap_at == 1 else wrap(line, wrap_at)
                 for sline in sub_lines:
                     self._stream.write(prefix + sline + '\n')
             self._stream.write(indent_current * self._c + ')')

tests/test_prettier.py

@@ -513,3 +513,55 @@ def test_ast_expr():
 
 def test_ast_module():
     assert pformat(ast.parse('print(1, 2, round(3))')).startswith('Module(\n    body=[')
+
+
+@pytest.mark.parametrize('width', [7, 11, 15])
+@pytest.mark.parametrize('value', ['abcdefghijk', b'abcdefghijk'])
+def test_nested_string_exhausted_width(width: int, value: str | bytes):
+    output = PrettyFormat(width=width)([value])
+    assert ast.literal_eval(output) == [value]
+
+
+@pytest.mark.parametrize('width', [7, 11, 15])
+def test_nested_bytearray_exhausted_width(width: int):
+    value = bytearray(b'abcdefghijk')
+    output = PrettyFormat(width=width)([value])
+    node = ast.parse(output, mode='eval').body
+    assert isinstance(node, ast.List)
+    call = node.elts[0]
+    assert isinstance(call, ast.Call)
+    assert ast.literal_eval(call.args[0]) == bytes(value)
+
+
+@pytest.mark.parametrize('width', [12, 120])
+@pytest.mark.parametrize('depth', [2, 30])
+@pytest.mark.parametrize('highlight', [False, True])
+def test_nested_raw_repr_exhausted_width(width: int, depth: int, highlight: bool):
+    class LongRepr:
+        def __repr__(self) -> str:
+            return 'Custom(value=' + 'x' * 120 + ')'
+
+    leaf = LongRepr()
+    value: Any = leaf
+    for _ in range(depth):
+        value = [value]
+    output = PrettyFormat(width=width)(value, highlight=highlight)
+    assert repr(leaf) in ''.join(strip_ansi(output).split())
+
+
+@pytest.mark.parametrize('width,depth', [(12, 2), (13, 2), (120, 30)])
+@pytest.mark.parametrize('highlight', [False, True])
+@pytest.mark.parametrize('payload', ['alpha beta  gamma', ' leading and trailing ', 'alpha\tbeta'])
+def test_exhausted_raw_repr_preserves_whitespace(width: int, depth: int, highlight: bool, payload: str):
+    class RawRepr:
+        def __repr__(self) -> str:
+            return f"Custom('{payload}')"
+
+    leaf = RawRepr()
+    value: Any = leaf
+    for _ in range(depth):
+        value = [value]
+    output = strip_ansi(PrettyFormat(width=width)(value, highlight=highlight))
+    prefix = ' ' * ((depth + 1) * 4)
+    content = ''.join(line[len(prefix) :] for line in output.splitlines() if line.startswith(prefix))
+    assert content == repr(leaf)