test(detox): cleanly close the test session, fetch coverage file

prior to this the app was never requested to close, so the Activity hung
until killed, with no control given to the app and no ability to finish up (or dump coverage)

after the run we need to fetch the native coverage file for further processing

Author: mikehardy

tests/e2e/init.js

@@ -18,6 +18,7 @@
 require('./globals');
 
 const detox = require('detox');
+const { execSync } = require('child_process');
 const jet = require('jet/platform/node');
 
 const { detox: config } = require('../package.json');
@@ -51,5 +52,29 @@ beforeEach(async function beforeEach() {
 
 after(async function () {
   console.log(' ✨ Tests Complete ✨ ');
+  const isAndroid = detox.device.getPlatform() === 'android';
+
+  // emits 'cleanup' across socket, which goes native, terminates Detox test Looper
+  // This returns control to the java code in our instrumented test, and then Instrumentation lifecycle finishes cleanly
+  await detox.cleanup();
+
+  // Get the file off the device, into standard location for JaCoCo binary report
+  // It will still need processing via gradle jacocoAndroidTestReport task for codecov, but it's available now
+  if (isAndroid) {
+    const pkg = 'com.invertase.testing';
+    const emuOrig = `/data/data/${pkg}/files/coverage.ec`;
+    const emuDest = '/data/local/tmp/detox/coverage.ec';
+    const localDestDir = './android/app/build/output/coverage/';
+
+    try {
+      execSync(`adb shell "run-as ${pkg} cat ${emuOrig} > ${emuDest}"`);
+      execSync(`mkdir -p ${localDestDir}`);
+      execSync(`adb pull ${emuDest} ${localDestDir}/emulator_coverage.ec`);
+      console.log(`Coverage data downloaded to: ${localDestDir}/emulator_coverage.ec`);
+    } catch (e) {
+      console.log('Unable to download coverage data from device: ', e);
+    }
+  }
+
   await device.terminateApp();
 });