Warn user when trying to spin run test.py

.github/workflows/test.sh

@@ -22,12 +22,14 @@ if [[ ${SPIN_PYTHONPATH} == "\$PYTHONPATH" ]]; then
     echo "Expected Python path, but got $SPIN_PYTHONPATH instead"
     exit 1
 fi
+
 echo -e "${MAGENTA}Does \$PYTHONPATH contains site-packages?${NORMAL}"
 if [[ ${SPIN_PYTHONPATH} == *"site-packages" ]]; then
     echo "Yes"
 else
     echo "No; it is $SPIN_PYTHONPATH"
 fi
+
 echo -e "${MAGENTA}Does \`spin run\` redirect only command output to stdout?${NORMAL}"
 # Once we're on Python >3.11, can replace syspath manipulation below with -P flag to Python
 VERSION=$(spin run python -c 'import sys; del sys.path[0]; import example_pkg; print(example_pkg.__version__)')
@@ -38,6 +40,20 @@ else
     exit 1
 fi
 
+if [[ $PLATFORM == linux || $PLATFORM == darwin ]]; then
+    # Detecting whether a file is executable is not that easy on Windows,
+    # as it seems to take into consideration whether that file is associated as an executable.
+    echo -e "${MAGENTA}Does \`spin run foo.py\` warn that \`spin run python foo.py\` is correct?${NORMAL}"
+    OUT=$( touch __foo.py && spin run __foo.py || true )
+    rm __foo.py
+    if [[ $OUT == *"Did you mean to call"* ]]; then
+        echo "Yes"
+    else
+        echo "No, output is: $OUT"
+        exit 1
+    fi
+fi
+
 prun spin test
 echo -e "${MAGENTA}Running \`spin test\`, but with PYTHONPATH set${NORMAL}"
 PYTHONPATH=./tmp spin test

spin/cmds/meson.py

@@ -1,4 +1,5 @@
 import contextlib
+import copy
 import json
 import os
 import shutil
@@ -496,15 +497,28 @@ def run(ctx, args):
 
     is_posix = sys.platform in ("linux", "darwin")
     shell = len(args) == 1
+    cmd_args = copy.copy(args)
     if shell:
-        args = args[0]
-
-    if shell and not is_posix:
-        # On Windows, we're going to try to use bash
-        args = ["bash", "-c", args]
+        cmd_args = args[0]
+        if not is_posix:
+            # On Windows, we're going to try to use bash
+            cmd_args = ["bash", "-c", cmd_args]
 
     _set_pythonpath(quiet=True)
-    _run(args, echo=False, shell=shell)
+    p = _run(cmd_args, echo=False, shell=shell, sys_exit=False)
+
+    # Is the user trying to run a Python script, without calling the Python interpreter?
+    executable = args[0]
+    if (
+        (p.returncode != 0)
+        and args[0].endswith(".py")
+        and os.path.exists(executable)
+        and (not os.access(executable, os.X_OK))
+    ):
+        click.secho(
+            f"Did you mean to call `spin run python {' '.join(args)}`?", fg="bright_red"
+        )
+    sys.exit(p.returncode)
 
 
 @click.command()