Add ability to pass down arguments + test.

tests/test_tutorial/test_options/test_help/prog_name.py

@@ -0,0 +1,14 @@
+import typer
+
+import subprocess
+
+app = typer.Typer()
+
+
+@app.command()
+def main(i: int):
+    pass
+
+
+if __name__ == "__main__":
+    app(prog_name="custom-name")

tests/test_tutorial/test_options/test_help/test_prog_name.py

@@ -0,0 +1,11 @@
+import subprocess
+
+
+def test_custom_prog_name():
+    result = subprocess.run(
+        ["python", "prog_name.py", "--help"],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        encoding="utf-8",
+    )
+    assert "custom-name" in result

typer/main.py

@@ -209,8 +209,8 @@ def add_typer(
             )
         )
 
-    def __call__(self) -> Any:
-        return get_command(self)()
+    def __call__(self, *args: Any, **kwargs: Any) -> Any:
+        return get_command(self)(*args, **kwargs)
 
 
 def get_group(typer_instance: Typer) -> click.Command: