Robotium APK Tests Running succesfuly with Android Studio. But While running with gradle, Issue occurs

[Naidu A]

Hi,

I encountered an issue while trying run few android tests with gradle.

The same project when i run through android studio & select as android tests, runs succesfully.

screenshot attached for the configurations i chosed.

But i want to use gradle to run my tests. My output looks like this:

:GameStoreApplicationTest:connectedAndroidTestDebug

Tests on Nexus_5_API_22_x86(AVD) - 5.1 failed: Instrumentation run failed due to 'java.lang.ClassNotFoundException'

com.android.builder.testing.ConnectedDevice > No tests found.[Nexus_5_API_22_x86(AVD) - 5.1] 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).

:GameStoreApplicationTest:connectedAndroidTestDebug FAILED

FAILURE: Build failed with an exception.

Not sure where i am doing wrong?

my build.gradle file looks like this:

buildscript {
    repositories {
        mavenCentral()
        flatDir {
            dirs 'libs'
        }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:1.0.0'
    }
}

apply plugin: 'com.android.application'

repositories {
   mavenCentral()
    flatDir {
        dirs 'libs'
    }
}

dependencies {
    androidTestCompile fileTree(dir: 'libs', include: 'robotium-solo-5.4.1.jar')
}

android {
    compileSdkVersion 'android-19'
    buildToolsVersion '19.1'

    android {
        defaultConfig {
            minSdkVersion 15
        }

        lintOptions {
            abortOnError false
        }
        sourceSets
                {
                    androidTest
                            {
                                res.srcDirs = ['res']
                                assets.srcDirs = ['assets']
                            }
                }
    }
    buildTypes {
        release {
            proguardFile getDefaultProguardFile('proguard-android.txt')
        }
    }
}

My manifest.xml looks like this:

<?xml version="1.0" encoding="utf-8" standalone="no"?><manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionCode="1" android:versionName="1.0" package="com.xxx.yyy.zzz">
    <application android:icon="@drawable/ic_launcher" android:label="@string/app_name">
        <activity android:label="@string/app_name" android:name="GameStoreActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
    </application>
<instrumentation android:name="android.test.InstrumentationTestRunner" android:targetPackage="com.xxx.yyy.zzz"/></manifest>