fix(python): bin script python support, test argument passing (#3762)

Corrects multiple issues with running `bin` scripts from python.

These were discovered in the context of this `projen` issue: projen/projen#2103

 - Corrects broken argument marshaling to binary scripts introduced in #3694
 - Exposes exit code and stderr from script execution instead of failing silently

Additionally, adds more robust test coverage of passing arguments to `bin` scripts.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license].

[Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0

.all-contributorsrc

@@ -1466,6 +1466,15 @@
       "contributions": [
         "bug"
       ]
+    },
+    {
+      "login": "jmalins",
+      "name": "Jeff Malins",
+      "avatar_url": "https://avatars.githubusercontent.com/u/2001356?v=4",
+      "profile": "https://github.com/jmalins",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "repoType": "github",

packages/@jsii/kernel/src/kernel.test.ts

@@ -2144,10 +2144,27 @@ defineTest('invokeBinScript() return output', (sandbox) => {
     script: 'calc',
   });
 
-  expect(result.stdout).toEqual('Hello World!\n');
-  expect(result.stderr).toEqual('');
-  expect(result.status).toEqual(0);
-  expect(result.signal).toBeNull();
+  expect(result).toMatchObject<api.InvokeScriptResponse>({
+    status: 0,
+    stdout: 'Hello World!\n',
+    stderr: '',
+    signal: null,
+  });
+});
+
+defineTest('invokeBinScript() accepts arguments', (sandbox) => {
+  const result = sandbox.invokeBinScript({
+    assembly: 'jsii-calc',
+    script: 'calc',
+    args: ['arg1', 'arg2'],
+  });
+
+  expect(result).toMatchObject<api.InvokeScriptResponse>({
+    status: 0,
+    stdout: 'Hello World!\n  arguments: arg1, arg2\n',
+    stderr: '',
+    signal: null,
+  });
 });
 
 // =================================================================================================

packages/@jsii/python-runtime/src/jsii/_runtime.py

@@ -1,9 +1,10 @@
 import abc
 import os
+import sys
 
 import attr
 
-from typing import cast, Any, Callable, List, Optional, Mapping, Type, TypeVar
+from typing import Sequence, cast, Any, Callable, List, Optional, Mapping, Type, TypeVar
 
 from . import _reference_map
 from ._compat import importlib_resources
@@ -47,10 +48,23 @@ def load(cls, *args, _kernel=kernel, **kwargs) -> "JSIIAssembly":
 
     @classmethod
     def invokeBinScript(
-        cls, pkgname: str, script: str, *args: str, _kernel=kernel
-    ) -> None:
+        cls,
+        pkgname: str,
+        script: str,
+        args: Optional[Sequence[str]] = None,
+        _kernel=kernel,
+    ) -> int:
+        if args is None:
+            args = []
+
         response = _kernel.invokeBinScript(pkgname, script, args)
-        print(response.stdout)
+        if response.stdout:
+            print(response.stdout)
+
+        if response.stderr:
+            print(response.stderr, file=sys.stderr)
+
+        return response.status
 
 
 class JSIIMeta(_ClassPropertyMeta, type):

packages/@jsii/python-runtime/tests/test_invoke_bin.py

@@ -0,0 +1,38 @@
+import platform
+import subprocess
+import sys
+import pytest
+
+
+class TestInvokeBinScript:
+    @pytest.mark.skipif(
+        platform.system() == "Windows",
+        reason="jsii-pacmak does not generate windows scripts",
+    )
+    def test_invoke_script(self) -> None:
+        result = run_script("calc")
+
+        assert result.returncode == 0
+        assert result.stdout == b"Hello World!\n\n"
+        assert result.stderr == b""
+
+    @pytest.mark.skipif(
+        platform.system() == "Windows",
+        reason="jsii-pacmak does not generate windows scripts",
+    )
+    def test_invoke_script_with_args(self) -> None:
+        result = run_script("calc", "arg1", "arg2")
+
+        assert result.returncode == 0
+        assert result.stdout == b"Hello World!\n  arguments: arg1, arg2\n\n"
+        assert result.stderr == b""
+
+
+def run_script(script_name: str, *args: str) -> subprocess.CompletedProcess:
+    if platform.system() == "Windows":
+        # currently not used, the calling semantics have not been defined for bin scripts on windows
+        script_path = f".env\\Scripts\\{script_name}"
+        return subprocess.run([sys.executable, script_path, *args], capture_output=True)
+    else:
+        script_path = f".env/bin/{script_name}"
+        return subprocess.run([script_path, *args], capture_output=True)

packages/jsii-calc/bin/run.ts

@@ -3,3 +3,8 @@
 /* eslint-disable no-console */
 
 console.info('Hello World!');
+
+const args = process.argv.slice(2);
+if (args.length > 0) {
+  console.info(`  arguments: ${args.join(', ')}`);
+}

packages/jsii-pacmak/lib/targets/python.ts

@@ -1792,14 +1792,15 @@ class PythonModule implements PythonType {
           code.line();
           emitList(
             code,
-            '__jsii_assembly__.invokeBinScript(',
+            'exit_code = __jsii_assembly__.invokeBinScript(',
             [
               JSON.stringify(this.assembly.name),
               JSON.stringify(name),
               'sys.argv[1:]',
             ],
             ')',
           );
+          code.line('exit(exit_code)');
           code.closeFile(script_file);
           scripts.push(script_file.replace(/\\/g, '/'));
         }