如何解决gradle任务中的“找不到符号”

Question

我试图运行gradle任务“ compileUnitTestJava”，但我总是收到“找不到符号”的错误，并且我不明白为什么。

我只能向您显示一个与真实项目具有相同错误的Testproject，因为它的正常工作和真实代码无法发布。

MainActivity：

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public int test(){
        return 5;
    }
}

测试类：

package com.example.testapplication;

import org.junit.Test;

import static org.junit.Assert.*;

public class MainActivityTest {

    @Test
    public void test1() {
        MainActivity ma = new MainActivity();
        assertEquals(5, ma.test());
    }
}

build.gradle：

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.testapplication"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

    lintOptions {
        abortOnError false
    }
}

sourceSets {
    unitTest {
        java {
            srcDirs = ['src/test/java']
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    testImplementation 'junit:junit:4.12'
    unitTestImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}


task abcdefg(type:Test, dependsOn: 'assemble') {
    testClassesDirs = project.sourceSets.unitTest.output.classesDirs
    classpath = project.sourceSets.unitTest.runtimeClasspath
}

这些错误总是在发生。

> Task :app:compileUnitTestJava FAILED
C:\Users\nne\Downloads\TestApplication\app\src\test\java\com\example\testapplication\MainActivityTest.java:11: error: cannot find symbol
        MainActivity ma = new MainActivity();
        ^
  symbol:   class MainActivity
  location: class MainActivityTest
C:\Users\nne\Downloads\TestApplication\app\src\test\java\com\example\testapplication\MainActivityTest.java:11: error: cannot find symbol
        MainActivity ma = new MainActivity();
                              ^
  symbol:   class MainActivity
  location: class MainActivityTest
2 errors