Support passing prog_name

tests/assets/prog_name.py

@@ -0,0 +1,12 @@
+import typer
+
+app = typer.Typer()
+
+
+@app.command()
+def main(i: int):  # pragma: no cover
+    pass
+
+
+if __name__ == "__main__":
+    app(prog_name="custom-name")

tests/test_prog_name.py

@@ -0,0 +1,13 @@
+import subprocess
+from pathlib import Path
+
+
+def test_custom_prog_name():
+    file_path = Path(__file__).parent / "assets/prog_name.py"
+    result = subprocess.run(
+        ["coverage", "run", str(file_path), "--help"],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+        encoding="utf-8",
+    )
+    assert "Usage: custom-name [OPTIONS] I" in result.stdout

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: