I'm trying to get my instrumentation tests running on Travis CI. I'm getting this error when the build runs on Travis. However, I don't have any problems running the tests locally. I'm new to Android/Java development so I'm not even sure where to start looking.
...
:MyappAndroid:packageMyappDebugAndroidTest
:MyappAndroid:assembleMyappDebugAndroidTest
:MyappAndroid:connectedMyappDebugAndroidTest
Tests on test(AVD) - 6.0 failed: Instrumentation run failed due to 'java.io.FileNotFoundException'
com.android.builder.testing.ConnectedDevice > No tests found.[test(AVD) - 6.0] FAILED 
No tests found. This usually means that your test classes are not in the form that your test runner expects (e.g. don't inherit from TestCase or lack @Test annotations).
:MyappAndroid:connectedMyappDebugAndroidTest FAILED
...
Here is one of my tests that I expect to run:
package core.ui.dialogs;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import android.support.test.rule.ActivityTestRule;
import android.support.test.runner.AndroidJUnit4;
@RunWith(AndroidJUnit4.class)
@LargeTest
public class DialogActivityTest {
    @Rule
    public ActivityTestRule<DialogActivity> mActivityRule = new ActivityTestRule<>(DialogActivity.class);
    @Test
    public void testSomething() {
        // etc...
    }
}
My .travis.yml:
language: android
jdk: oraclejdk7
sudo: false
env:
  global:
    - ANDROID_API_LEVEL=23
    - BUILD_TOOLS_VERSION=23.0.3
    - ANDROID_ABI=armeabi-v7a
    - ADB_INSTALL_TIMEOUT=8
android:
  components:
    - tools
    - build-tools-$BUILD_TOOLS_VERSION
    - android-$ANDROID_API_LEVEL
    - add-on
    - extra
before_script:
  - echo no | android create avd --force -n test -t android-$ANDROID_API_LEVEL --abi $ANDROID_ABI
  - emulator -avd test -no-skin -no-audio -no-window &
  - android-wait-for-emulator
  - adb shell input keyevent 82 &
script: ./gradlew assembleMyappDebug connectedMyappDebugAndroidTest -PdisablePreDex
Update: Here are a few things that may be relevant in my build.gradle:
android {
    compileSdkVersion 23
    buildToolsVersion "23.0.3"
    defaultConfig {
        minSdkVersion 19
        targetSdkVersion 23
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
}
// ...
dependencies {
    compile 'com.android.support:appcompat-v7:23.1.0'
    compile 'com.android.support:support-v4:23.1.0'
    compile 'com.google.android.gms:play-services-gcm:8.4.0'
    compile 'com.google.code.gson:gson:2.3'
    compile 'com.squareup.dagger:dagger:1.2.2'
    provided 'com.squareup.dagger:dagger-compiler:1.2.2'
    // ...
    androidTestCompile 'com.squareup:javawriter:2.5.0'
    androidTestCompile ('com.android.support.test.espresso:espresso-core:2.0') {
        exclude group: 'javax.inject'
    }
    androidTestCompile 'com.android.support.test:testing-support-lib:0.1'
 }