Add instrumentation test for testing AES/GCM nonces are really unique

app/build.gradle

@@ -37,6 +37,15 @@ android {
         }
     }
 
+    sourceSets {
+        test {
+            java.srcDirs += "$projectDir/src/sharedTest/java"
+        }
+        androidTest {
+            java.srcDirs += "$projectDir/src/sharedTest/java"
+        }
+    }
+
     // optional signingConfigs
     def keystorePropertiesFile = rootProject.file("keystore.properties")
     if (keystorePropertiesFile.exists()) {

app/src/androidTest/java/com/stevesoltys/backup/CipherUniqueNonceTest.kt

@@ -0,0 +1,33 @@
+package com.stevesoltys.backup
+
+import android.util.Log
+import androidx.test.filters.LargeTest
+import androidx.test.runner.AndroidJUnit4
+import com.stevesoltys.backup.crypto.CipherFactoryImpl
+import com.stevesoltys.backup.crypto.KeyManagerTestImpl
+import org.junit.Assert.assertTrue
+import org.junit.Test
+import org.junit.runner.RunWith
+
+private val TAG = CipherUniqueNonceTest::class.java.simpleName
+private const val ITERATIONS = 1_000_000
+
+@LargeTest
+@RunWith(AndroidJUnit4::class)
+class CipherUniqueNonceTest {
+
+    private val keyManager = KeyManagerTestImpl()
+    private val cipherFactory = CipherFactoryImpl(keyManager)
+
+    private val nonceSet = HashSet<ByteArray>()
+
+    @Test
+    fun testUniqueNonce() {
+        for (i in 1..ITERATIONS) {
+            val iv = cipherFactory.createEncryptionCipher().iv
+            Log.w(TAG, "$i: ${iv.toHexString()}")
+            assertTrue(nonceSet.add(iv))
+        }
+    }
+
+}

app/src/androidTest/java/com/stevesoltys/backup/DocumentsStorageTest.kt

@@ -17,7 +17,7 @@ import kotlin.random.Random
 private const val filename = "test-file"
 
 @RunWith(AndroidJUnit4::class)
-class AndroidUnitTest {
+class DocumentsStorageTest {
 
     private val context = InstrumentationRegistry.getInstrumentation().targetContext
     private val folderUri = getBackupFolderUri(context)

app/src/sharedTest/java/com/stevesoltys/backup/TestUtils.kt

@@ -1,11 +1,9 @@
 package com.stevesoltys.backup
 
-import org.junit.jupiter.api.Assertions.assertTrue
-import org.junit.jupiter.api.Assertions.fail
 import kotlin.random.Random
 
 fun assertContains(stack: String?, needle: String) {
-    assertTrue(stack?.contains(needle) ?: fail())
+    if (stack?.contains(needle) != true) throw AssertionError()
 }
 
 fun getRandomByteArray(size: Int = Random.nextInt(1337)) = ByteArray(size).apply {