Refactor pyexec (#1318)

This is some refactoring I did on the way towards resolving pyscript#1313.
I added a new _run_pyscript Python function which executes the code
inside a context manager that sets the display target. We can then
return a JS object wrapper directly from Python.

I moved the "installation" of the pyscript module to loadInterpreter,
and pyimport pyscript_py there and give it a type. This avoids a bunch
of creating and deleting of proxies for pyscript_py and allows us to
give it a type once and for all.

I also did some minor logic cleanup in a few places.

pyscriptjs/tests/py-unit/conftest.py

@@ -6,10 +6,6 @@ import pytest
 
 pyscriptjs = Path(__file__).parents[2]
 
-import pytest  # noqa
-
-pyscriptjs = Path(__file__).parents[2]
-
 # add pyscript folder to path
 python_source = pyscriptjs / "src" / "python"
 sys.path.append(str(python_source))
@@ -18,6 +14,7 @@ sys.path.append(str(python_source))
 python_plugins_source = pyscriptjs / "src" / "plugins" / "python"
 sys.path.append(str(python_plugins_source))
 
+
 # patch pyscript module where needed
 import pyscript  # noqa: E402
 import pyscript_plugins_tester as ppt  # noqa: E402

pyscriptjs/tests/py-unit/micropip.py

@@ -1,4 +0,0 @@
-"""Mock module that emulates some of the pyodide js module features for the sake of tests"""
-from unittest.mock import Mock
-
-install = Mock()

pyscriptjs/tests/py-unit/pyodide/ffi.py

@@ -1,4 +0,0 @@
-"""Mock module that emulates some of the pyodide js module features for the sake of tests"""
-from unittest.mock import Mock
-
-create_proxy = Mock(side_effect=lambda x: x)

pyscriptjs/tests/py-unit/pyodide/pyodide.py

@@ -1,4 +0,0 @@
-"""Mock module that emulates some of the pyodide js module features for the sake of tests"""
-from unittest.mock import Mock
-
-create_proxy = Mock(side_effect=lambda x: x)

pyscriptjs/tests/unit/pyodide.test.ts

@@ -1,18 +1,26 @@
 import type { AppConfig } from '../../src/pyconfig';
 import { InterpreterClient } from '../../src/interpreter_client';
-import { RemoteInterpreter } from '../../src/remote_interpreter';
 import { CaptureStdio } from '../../src/stdio';
 import * as Synclink from 'synclink';
 import { describe, beforeAll, afterAll, it, expect } from '@jest/globals';
+// We can't import RemoteInterpreter at top level because we need to mock the
+// Python package in setup.ts
+// But we can import the types at top level.
+// TODO: is there a better way to handle this?
+import type { RemoteInterpreter } from '../../src/remote_interpreter';
 
 describe('RemoteInterpreter', () => {
     let interpreter: InterpreterClient;
     let stdio: CaptureStdio = new CaptureStdio();
+    let RemoteInterpreter;
     const { port1, port2 } = new MessageChannel();
     beforeAll(async () => {
         const SRC = '../pyscriptjs/node_modules/pyodide/pyodide.js';
         const config: AppConfig = { interpreters: [{ src: SRC }] };
+        // Dynamic import of RemoteInterpreter sees our mocked Python package.
+        ({ RemoteInterpreter } = await import('../../src/remote_interpreter'));
         const remote_interpreter = new RemoteInterpreter(SRC);
+
         port1.start();
         port2.start();
         Synclink.expose(remote_interpreter, port2);

pyscriptjs/tests/unit/setup.ts

@@ -0,0 +1,6 @@
+import { jest } from '@jest/globals';
+import { directoryManifest } from '../../directoryManifest.mjs';
+
+jest.unstable_mockModule('../../src/python_package', async () => ({
+    python_package: await directoryManifest('./src/python/'),
+}));