Fix - as filename feature (#1005)

* Exemption from absolute filepath if filename is -

* Comment why filepath is not made absolute if - is filename.

* Add a test for `-` as filename feature.

* Fix typo

* Use subprocess instead of echo and pipe for test.

* Run black

* Removed unused shell mode argument.

Author: Aathish04

manim/_config/utils.py

@@ -605,7 +605,9 @@ def digest_args(self, args: argparse.Namespace) -> "ManimConfig":
         if args.config_file:
             self.digest_file(args.config_file)
 
-        self.input_file = Path(args.file).absolute()
+        # If args.file is `-`, the animation code has to be taken from STDIN, so the
+        # input file path shouldn't be absolute, since that file won't be read.
+        self.input_file = Path(args.file).absolute() if args.file != "-" else args.file
         self.scene_names = args.scene_names if args.scene_names is not None else []
         self.output_file = args.output_file
 

tests/test_scene_rendering/test_cli_flags.py

@@ -164,3 +164,22 @@ def test_custom_folders(tmp_path, manim_cfg_file, simple_scenes_path):
 
     exists = (tmp_path / "SquareToCircle.png").exists()
     assert exists, "--custom_folders did not produce the output file"
+
+
+@pytest.mark.slow
+def test_dash_as_filename(tmp_path):
+    code = "class Test(Scene):\n    def construct(self):\n        self.add(Circle())\n        self.wait(1)"
+    command = [
+        "python",
+        "-m",
+        "manim",
+        "-ql",
+        "-s",
+        "--media_dir",
+        str(tmp_path),
+        "-",
+    ]
+    out, err, exit_code = capture(command, command_input=code)
+    assert exit_code == 0, err
+    exists = (tmp_path / "images" / "-" / "Test.png").exists()
+    assert exists, out

tests/utils/commands.py

@@ -1,13 +1,14 @@
 import subprocess
 
 
-def capture(command, cwd=None):
+def capture(command, cwd=None, command_input=None):
     proc = subprocess.Popen(
         command,
         stdout=subprocess.PIPE,
         stderr=subprocess.PIPE,
+        stdin=subprocess.PIPE,
         encoding="utf8",
         cwd=cwd,
     )
-    out, err = proc.communicate()
+    out, err = proc.communicate(command_input)
     return out, err, proc.returncode