diff --git a/tests/test_command_line.py b/tests/test_command_line.py
index b3e0b09..10784d5 100644
--- a/tests/test_command_line.py
+++ b/tests/test_command_line.py
@@ -21,22 +21,23 @@ LOG: bytes = (
     b"INFO Drawing extra icons...\n"
     b"INFO Drawing texts...\n"
 )
+OUTPUT_PATH: Path = Path("out")
 
 
 def error_run(arguments: list[str], message: bytes) -> None:
     """Run command that should fail and check error message."""
     with Popen(["map-machine"] + arguments, stderr=PIPE) as pipe:
-        _, error = pipe.communicate()
+        _, output = pipe.communicate()
+        assert output == message
         assert pipe.returncode != 0
-        assert error == message
 
 
 def run(arguments: list[str], message: bytes) -> None:
-    """Run command that should fail and check error message."""
+    """Run command that should not fail and check output."""
     with Popen(["map-machine"] + arguments, stderr=PIPE) as pipe:
-        _, error = pipe.communicate()
+        _, output = pipe.communicate()
+        assert output == message
         assert pipe.returncode == 0
-        assert error == message
 
 
 def test_wrong_render_arguments() -> None:
@@ -54,10 +55,10 @@ def test_render() -> None:
         COMMAND_LINES["render"] + ["--cache", "tests/data"],
         LOG + b"INFO Writing output SVG to out/map.svg...\n",
     )
-    with Path("out/map.svg").open(encoding="utf-8") as output_file:
+    with (OUTPUT_PATH / "map.svg").open(encoding="utf-8") as output_file:
         root: Element = ElementTree.parse(output_file).getroot()
 
-    # 4 expected elements: `defs`, `rect` (background), `g` (outline),
+    # 8 expected elements: `defs`, `rect` (background), `g` (outline),
     # `g` (icon), 4 `text` elements (credits).
     assert len(root) == 8
     assert len(root[3][0]) == 0
@@ -71,10 +72,10 @@ def test_render_with_tooltips() -> None:
         COMMAND_LINES["render_with_tooltips"] + ["--cache", "tests/data"],
         LOG + b"INFO Writing output SVG to out/map.svg...\n",
     )
-    with Path("out/map.svg").open(encoding="utf-8") as output_file:
+    with (OUTPUT_PATH / "map.svg").open(encoding="utf-8") as output_file:
         root: Element = ElementTree.parse(output_file).getroot()
 
-    # 4 expected elements: `defs`, `rect` (background), `g` (outline),
+    # 8 expected elements: `defs`, `rect` (background), `g` (outline),
     # `g` (icon), 4 `text` elements (credits).
     assert len(root) == 8
     assert len(root[3][0]) == 1
@@ -91,12 +92,11 @@ def test_icons() -> None:
         b"INFO Icon grid is written to out/icon_grid.svg.\n"
         b"INFO Icon grid is written to doc/grid.svg.\n",
     )
-
-    assert (Path("out") / "icon_grid.svg").is_file()
-    assert (Path("out") / "icons_by_name").is_dir()
-    assert (Path("out") / "icons_by_id").is_dir()
-    assert (Path("out") / "icons_by_name" / "Röntgen apple.svg").is_file()
-    assert (Path("out") / "icons_by_id" / "apple.svg").is_file()
+    assert (OUTPUT_PATH / "icon_grid.svg").is_file()
+    assert (OUTPUT_PATH / "icons_by_name").is_dir()
+    assert (OUTPUT_PATH / "icons_by_id").is_dir()
+    assert (OUTPUT_PATH / "icons_by_name" / "Röntgen apple.svg").is_file()
+    assert (OUTPUT_PATH / "icons_by_id" / "apple.svg").is_file()
 
 
 def test_mapcss() -> None:
@@ -105,9 +105,8 @@ def test_mapcss() -> None:
         COMMAND_LINES["mapcss"],
         b"INFO MapCSS 0.2 scheme is written to out/map_machine_mapcss.\n",
     )
-    out_path: Path = Path("out") / "map_machine_mapcss"
+    out_path: Path = OUTPUT_PATH / "map_machine_mapcss"
 
-    assert out_path.is_dir()
     assert out_path.is_dir()
     assert (out_path / "icons" / "apple.svg").is_file()
     assert (out_path / "map_machine.mapcss").is_file()
@@ -120,7 +119,7 @@ def test_element() -> None:
         COMMAND_LINES["element"],
         b"INFO Element is written to out/element.svg.\n",
     )
-    assert (Path("out") / "element.svg").is_file()
+    assert (OUTPUT_PATH / "element.svg").is_file()
 
 
 def test_unwrapped_element() -> None:
@@ -140,5 +139,5 @@ def test_tile() -> None:
         b"INFO SVG file is rasterized to out/tiles/tile_18_160199_88904.png.\n",
     )
 
-    assert (Path("out") / "tiles" / "tile_18_160199_88904.svg").is_file()
-    assert (Path("out") / "tiles" / "tile_18_160199_88904.png").is_file()
+    assert (OUTPUT_PATH / "tiles" / "tile_18_160199_88904.svg").is_file()
+    assert (OUTPUT_PATH / "tiles" / "tile_18_160199_88904.png").is_file()