Make python -m pip work in cli runner even if we haven't sourced pyod…

…ide venv

src/templates/python

@@ -25,8 +25,11 @@ EOF
 set -e
 if [[ $1 == "-m" ]] && [[ $2 == "pip" ]]; then
     # redirect python -m pip to execute in host environment
-    shift 1
-    exec $@
+    shift 2
+    which $(dirname $0)/pip || { \
+        >&2 echo "Cannot find pyodide pip. Make a pyodide venv first?" && exit 1; \
+    }
+    exec $(dirname $0)/pip $@
 fi
 
 which node > /dev/null  || { \

src/tests/test_cmdline_runner.py

@@ -125,22 +125,16 @@ def test_dash_m(selenium):
 
 @only_node
 def test_dash_m_pip(selenium, monkeypatch, tmp_path):
-    import os
-
-    monkeypatch.setenv("PATH", str(tmp_path), prepend=":")
-    pip_path = tmp_path / "pip"
-    pip_path.write_text("echo 'pip got' $@")
-    os.chmod(pip_path, 0o777)
-
     result = subprocess.run(
         [script_path, "-m", "pip", "install", "pytest"],
         capture_output=True,
         encoding="utf8",
         check=False,
     )
-    assert result.returncode == 0
-    assert result.stderr == ""
-    assert result.stdout.strip() == "pip got install pytest"
+    assert result.returncode == 1
+    assert (
+        result.stderr.strip() == "Cannot find pyodide pip. Make a pyodide venv first?"
+    )
 
 
 @only_node
@@ -544,3 +538,25 @@ def test_cpp_exceptions(selenium, venv):
     print(result.stderr)
     assert result.returncode == 1
     assert "ImportError: oops" in result.stderr
+
+
+@only_node
+def test_dash_m_pip_venv(selenium, venv):
+    result = subprocess.run(
+        [venv / "bin/python", "-m", "pip", "install", "regex"],
+        capture_output=True,
+        encoding="utf8",
+        check=False,
+    )
+    assert result.returncode == 0
+    assert (
+        clean_pkg_install_stdout(result.stdout)
+        == dedent(
+            """
+            Looking in links: .../dist
+            Processing ./dist/regex-*-cpxxx-cpxxx-pyodide_*_wasm32.whl
+            Installing collected packages: regex
+            Successfully installed regex-*
+            """
+        ).strip()
+    )