gh-131531: android.py enhancements to support cibuildwheel (#132870)

Modifies the environment handling and execution arguments of the Android management
script to support the compilation of third-party binaries, and the use of the testbed to 
invoke third-party test code.

Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Russell Keith-Magee <russell@keith-magee.com>

Android/testbed/app/build.gradle.kts

@@ -85,7 +85,7 @@ android {
 
         minSdk = androidEnvFile.useLines {
             for (line in it) {
-                """api_level:=(\d+)""".toRegex().find(line)?.let {
+                """ANDROID_API_LEVEL:=(\d+)""".toRegex().find(line)?.let {
                     return@useLines it.groupValues[1].toInt()
                 }
             }
@@ -205,11 +205,29 @@ androidComponents.onVariants { variant ->
 
                 into("site-packages") {
                     from("$projectDir/src/main/python")
+
+                    val sitePackages = findProperty("python.sitePackages") as String?
+                    if (!sitePackages.isNullOrEmpty()) {
+                        if (!file(sitePackages).exists()) {
+                            throw GradleException("$sitePackages does not exist")
+                        }
+                        from(sitePackages)
+                    }
                 }
 
                 duplicatesStrategy = DuplicatesStrategy.EXCLUDE
                 exclude("**/__pycache__")
             }
+
+            into("cwd") {
+                val cwd = findProperty("python.cwd") as String?
+                if (!cwd.isNullOrEmpty()) {
+                    if (!file(cwd).exists()) {
+                        throw GradleException("$cwd does not exist")
+                    }
+                    from(cwd)
+                }
+            }
         }
     }
 

Android/testbed/app/src/androidTest/java/org/python/testbed/PythonSuite.kt

@@ -17,11 +17,11 @@ class PythonSuite {
     fun testPython() {
         val start = System.currentTimeMillis()
         try {
-            val context =
+            val status = PythonTestRunner(
                 InstrumentationRegistry.getInstrumentation().targetContext
-            val args =
-                InstrumentationRegistry.getArguments().getString("pythonArgs", "")
-            val status = PythonTestRunner(context).run(args)
+            ).run(
+                InstrumentationRegistry.getArguments()
+            )
             assertEquals(0, status)
         } finally {
             // Make sure the process lives long enough for the test script to

Android/testbed/app/src/main/java/org/python/testbed/MainActivity.kt

@@ -15,17 +15,29 @@ class MainActivity : AppCompatActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
-        val status = PythonTestRunner(this).run("-W -uall")
+        val status = PythonTestRunner(this).run("-m", "test", "-W -uall")
         findViewById<TextView>(R.id.tvHello).text = "Exit status $status"
     }
 }
 
 
 class PythonTestRunner(val context: Context) {
-    /** @param args Extra arguments for `python -m test`.
-     * @return The Python exit status: zero if the tests passed, nonzero if
-     * they failed. */
-    fun run(args: String = "") : Int {
+    fun run(instrumentationArgs: Bundle) = run(
+        instrumentationArgs.getString("pythonMode")!!,
+        instrumentationArgs.getString("pythonModule")!!,
+        instrumentationArgs.getString("pythonArgs") ?: "",
+    )
+
+    /** Run Python.
+     *
+     * @param mode Either "-c" or "-m".
+     * @param module Python statements for "-c" mode, or a module name for
+     *     "-m" mode.
+     * @param args Arguments to add to sys.argv. Will be parsed by `shlex.split`.
+     * @return The Python exit status: zero on success, nonzero on failure. */
+    fun run(mode: String, module: String, args: String) : Int {
+        Os.setenv("PYTHON_MODE", mode, true)
+        Os.setenv("PYTHON_MODULE", module, true)
         Os.setenv("PYTHON_ARGS", args, true)
 
         // Python needs this variable to help it find the temporary directory,
@@ -36,8 +48,9 @@ class PythonTestRunner(val context: Context) {
         System.loadLibrary("main_activity")
         redirectStdioToLogcat()
 
-        // The main module is in src/main/python/main.py.
-        return runPython(pythonHome.toString(), "main")
+        // The main module is in src/main/python. We don't simply call it
+        // "main", as that could clash with third-party test code.
+        return runPython(pythonHome.toString(), "android_testbed_main")
     }
 
     private fun extractAssets() : File {

Android/testbed/app/src/main/python/android_testbed_main.py

@@ -26,7 +26,23 @@
 #     test_signals in test_threadsignals.py.
 signal.pthread_sigmask(signal.SIG_UNBLOCK, [signal.SIGUSR1])
 
+mode = os.environ["PYTHON_MODE"]
+module = os.environ["PYTHON_MODULE"]
 sys.argv[1:] = shlex.split(os.environ["PYTHON_ARGS"])
 
-# The test module will call sys.exit to indicate whether the tests passed.
-runpy.run_module("test")
+cwd = f"{sys.prefix}/cwd"
+if not os.path.exists(cwd):
+    # Empty directories are lost in the asset packing/unpacking process.
+    os.mkdir(cwd)
+os.chdir(cwd)
+
+if mode == "-c":
+    # In -c mode, sys.path starts with an empty string, which means whatever the current
+    # working directory is at the moment of each import.
+    sys.path.insert(0, "")
+    exec(module, {})
+elif mode == "-m":
+    sys.path.insert(0, os.getcwd())
+    runpy.run_module(module, run_name="__main__", alter_sys=True)
+else:
+    raise ValueError(f"unknown mode: {mode}")