[main]: Add mdp to lecture notes

docs/lectures/mdp/16_app_testing.md

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+# App Optimisation, Testing & Deployment
+
+### Check Memory Usage
+
+- `abd shell dumpsys meminfo <package_name>`
+    - Check if memory size increased since launch
+    - Number of objects that have been created
+    - Database information
+- Terminology:
+    - Native Heap: memory used by the process itself
+    - Dalvik Heap: memory allocated by DalvikVM
+    - Dalvik Other: memory used for JIT
+    - Pss total: all connections to the main device memory thread
+    - Private dirty: actual amount of RAM the app is using on the heap since the app started
+
+### Code Optimisation
+
+- Minimise object creation
+- Make a method static if there is no need to modify the state of an object
+- Make any constants `static final`
+- `Int` is 2x faster than `float`
+- Use enhanced for loops (for-each instead of regular for loops)
+
+### App Testing
+
+![image-20220118165511824](img/cc.png)
+
+- Generally, developing tests is done before developing code
+
+#### Unit Tests
+
+- Build unit tests to verify the logic of specific code in the app
+- Local tests
+    - run on the local Java VM
+- Instrumented tests
+    - run based on the Android dependencies
+    - Can use `mockito` or `robolectric` to isolate a unit from its dependencies
+
+#### UI Tests
+
+- Test an entire sequence of events, user interface, end-to-end testing on emulators & devices
+
+- Tools: `AndroidJUnitRunner` & `Espresso API` & UI Automator
+
+- Modify `build.gradle`
+
+    ```groovy
+    dependencies{
+        androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
+    }
+    ```
+
+- Espresso records UI interactions and can use these to run a repeatable test automatically
+
+#### Monkey (stress test)
+
+- Runs on an emulator and generates pseudo-random streams of user events (clicks, touches, gestures and system-level events)
+
+```sh
+$ adb shell monkey [options] <event-count>
+$ adb shell monkey -p your.package.name -v 500
+```
+
+#### APK Generation
+
+- Use a good / unique *package name*
+    - `[org/com].[company].[product].[component]`
+- Build `->` Generate Signed APK
+
+##### Shrink Code & Resources (Proguard)
+
+```groovy
+buildTypes {
+    release {
+        minifyEnable true
+        shrinkResources true
+        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+    }
+}
+```
+
+Can try `proguard-android-optimize.txt` for more code shrinking