Download Python packages according to requested runtime

Packages should be downloaded for the Python version of the lambda's
runtime requested and not according to the version of the Python
interpreter running e3-aws.

src/e3/aws/troposphere/awslambda/__init__.py

@@ -412,12 +412,14 @@ def create_data_dir(self, root_dir: str) -> None:
 
         # Install the requirements
         if self.requirement_file is not None:
+            assert self.runtime is not None
             p = Run(
                 [
                     sys.executable,
                     "-m",
                     "pip",
                     "install",
+                    f"--python-version={self.runtime.lstrip('python')}",
                     f"--target={package_dir}",
                     "-r",
                     self.requirement_file,

tests/tests_e3_aws/troposphere/awslambda/awslambda_test.py

@@ -6,6 +6,8 @@
 import pytest
 import json
 import io
+from unittest.mock import patch
+import sys
 
 from flask import Flask, send_file
 from troposphere.awslambda import (
@@ -395,6 +397,39 @@ def test_pyfunction(stack: Stack) -> None:
     assert stack.export()["Resources"] == EXPECTED_PYFUNCTION_TEMPLATE
 
 
+def test_pyfunction_with_requirements(tmp_path, stack: Stack) -> None:
+    """Test PyFunction creation."""
+    stack.s3_bucket = "cfn_bucket"
+    stack.s3_key = "templates/"
+    code_dir = tmp_path
+
+    with patch("e3.aws.troposphere.awslambda.Run") as mock_run:
+        mock_run.return_value.status = 0
+        PyFunction(
+            name="mypylambda",
+            description="this is a test",
+            role="somearn",
+            runtime="python3.9",
+            code_dir=str(code_dir),
+            handler="app.main",
+            requirement_file="requirements.txt",
+        ).create_data_dir("dummy")
+    # Ensure the right pip command is called
+    mock_run.assert_called_once_with(
+        [
+            sys.executable,
+            "-m",
+            "pip",
+            "install",
+            "--python-version=3.9",
+            "--target=dummy/Mypylambda/package",
+            "-r",
+            "requirements.txt",
+        ],
+        output=None,
+    )
+
+
 def test_pyfunction_policy_document(stack: Stack) -> None:
     """Test cfn_policy_document of PyFunction."""
     stack.s3_bucket = "cfn_bucket"