java.lang.NullPointerException：無法獲取陰影爲null ShadowPreferenceManager

Question

有人可以幫助我理解如何解決此異常？

我引用Robolectric tests fail on shadowOf但我已經使用this訪問SharedPreferences即

SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);

@Config(emulateSdk = 18) 
@RunWith(RobolectricTestRunner.class) 
public class SomeClassTest { 

    private Context context; 
    private SomeClassTest someClassTest; 
    private SharedPreferences sharedPreferences; 

    @Before 
    public void setup() throws Exception { 
     context = mock(Context.class); 
     sharedPreferences = ShadowPreferenceManager.getDefaultSharedPreferences(context); 
     someClassTest = new SomeClassTest(context); 
    } 

    @Test 
    public void someClassProduction() { 
     when(someClassTest.getEnvironment()).thenReturn("PRODUCTION"); 
     when(someClassTest.getBaseUrl()).thenReturn("https://www.someUrl.com/v1/"); 
     assertTrue(someclassTest.getTestUrl().equals("https://www.someurl.com/v1/counts.json") 
    } 
} 

java.lang.NullPointerException: can't get a shadow for null 
    at org.robolectric.bytecode.ShadowWrangler.shadowOf(ShadowWrangler.java:442) 
    at org.robolectric.Robolectric.shadowOf_(Robolectric.java:1059) 
    at org.robolectric.Robolectric.shadowOf(Robolectric.java:477) 
    at org.robolectric.shadows.ShadowPreferenceManager.getDefaultSharedPreferences(ShadowPreferenceManager.java:21) 
    at android.preference.PreferenceManager.getDefaultSharedPreferences(PreferenceManager.java)

Answer 1

事實證明，我有context = Robolectric.application

更換context = mock(Context.class)這裏的更新測試：

@Config(emulateSdk = 18) 
@RunWith(RobolectricTestRunner.class) 
public class SomeClassTest { 

    private Context context; 
    private SomeClassTest someClassTest; 
    private SharedPreferences sharedPreferences; 

    @Before 
    public void setup() throws Exception { 
     context = Roboelectric.application; 
     sharedPreferences = ShadowPreferenceManager.getDefaultSharedPreferences(context); 
     someClassTest = new SomeClassTest(context); 
    } 

    @Test 
    public void someClassProduction() { 
     when(someClassTest.getEnvironment()).thenReturn("PRODUCTION"); 
     when(someClassTest.getBaseUrl()).thenReturn("https://www.someUrl.com/v1/"); 
     assertTrue(someclassTest.getTestUrl().equals("https://www.someurl.com/v1/counts.json") 
    } 
}