fix: check if the instrumentation process stops by sending a request

lib/uiautomator2.js

@@ -305,6 +305,26 @@ class UiAutomator2Server {
   async cleanupAutomationLeftovers (strictCleanup = false) {
     this.log.debug(`Performing ${strictCleanup ? 'strict' : 'shallow'} cleanup of automation leftovers`);
 
+    const waitStop = async () => {
+      // Wait for the process stop by sending a status request to the port.
+      // We observed the process stop could be delayed, then it caused the process stop
+      // in the middle of session preparation. It caused invalid session error response by the uia2 server,
+      // but that was because the process stop's delay.
+      const timeout = 3000;
+      try {
+        await waitForCondition(async () => {
+          try {
+            await this.jwproxy.command('/status', 'GET');
+          } catch (err) { return true; }
+        }, {
+          waitMs: timeout,
+          intervalMs: 100,
+        });
+      } catch (err) {
+        this.log.errorAndThrow(`The instrumentation process might fail to stop within ${timeout}ms timeout.`);
+      }
+    };
+
     try {
       const {value} = (await axios({
         url: `http://${this.host}:${this.systemPort}/sessions`,
@@ -330,12 +350,14 @@ class UiAutomator2Server {
       await this.adb.forceStop(SERVER_TEST_PACKAGE_ID);
     } catch (ignore) {}
     if (!strictCleanup) {
+      await waitStop();
       return;
     }
     // https://github.com/appium/appium/issues/10749
     try {
       await this.adb.killProcessesByName('uiautomator');
     } catch (ignore) {}
+    await waitStop();
   }
 }