Fix null context error in network utils (#2184)

Author: maskaravivek

app/src/main/java/fr/free/nrw/commons/utils/NetworkUtils.java

@@ -1,21 +1,34 @@
 package fr.free.nrw.commons.utils;
 
 
+import android.annotation.SuppressLint;
 import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 
+import javax.annotation.Nullable;
+
 public class NetworkUtils {
 
-    public static boolean isInternetConnectionEstablished(Context context) {
+    /**
+     * https://developer.android.com/training/monitoring-device-state/connectivity-monitoring#java
+     * Check if internet connection is established.
+     * @param context context passed to this method could be null.
+     * @return Returns current internet connection status. Returns false if null context was passed.
+     */
+    @SuppressLint("MissingPermission")
+    public static boolean isInternetConnectionEstablished(@Nullable Context context) {
+        if (context == null) {
+            return false;
+        }
+
         ConnectivityManager cm =
-                (ConnectivityManager)context.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
+                (ConnectivityManager) context.getApplicationContext().getSystemService(Context.CONNECTIVITY_SERVICE);
 
         if (cm == null) {
             return false;
         }
         NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
-        return activeNetwork != null &&
-                activeNetwork.isConnectedOrConnecting();
+        return activeNetwork != null && activeNetwork.isConnectedOrConnecting();
     }
 }

app/src/test/kotlin/fr/free/nrw/commons/utils/NetworkUtilsTest.java

@@ -0,0 +1,71 @@
+package fr.free.nrw.commons.utils;
+
+import android.app.Application;
+import android.content.Context;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class NetworkUtilsTest {
+
+    @Before
+    public void setUp() throws Exception {
+    }
+
+    @Test
+    public void testInternetConnectionEstablished() {
+        Context mockContext = mock(Context.class);
+        Application mockApplication = mock(Application.class);
+        ConnectivityManager mockConnectivityManager = mock(ConnectivityManager.class);
+        NetworkInfo mockNetworkInfo = mock(NetworkInfo.class);
+        when(mockNetworkInfo.isConnectedOrConnecting())
+                .thenReturn(true);
+        when(mockConnectivityManager.getActiveNetworkInfo())
+                .thenReturn(mockNetworkInfo);
+        when(mockApplication.getSystemService(Context.CONNECTIVITY_SERVICE))
+                .thenReturn(mockConnectivityManager);
+        when(mockContext.getApplicationContext()).thenReturn(mockApplication);
+        boolean internetConnectionEstablished = NetworkUtils.isInternetConnectionEstablished(mockContext);
+        assertTrue(internetConnectionEstablished);
+    }
+
+    @Test
+    public void testInternetConnectionNotEstablished() {
+        Context mockContext = mock(Context.class);
+        Application mockApplication = mock(Application.class);
+        ConnectivityManager mockConnectivityManager = mock(ConnectivityManager.class);
+        NetworkInfo mockNetworkInfo = mock(NetworkInfo.class);
+        when(mockNetworkInfo.isConnectedOrConnecting())
+                .thenReturn(false);
+        when(mockConnectivityManager.getActiveNetworkInfo())
+                .thenReturn(mockNetworkInfo);
+        when(mockApplication.getSystemService(Context.CONNECTIVITY_SERVICE))
+                .thenReturn(mockConnectivityManager);
+        when(mockContext.getApplicationContext()).thenReturn(mockApplication);
+        boolean internetConnectionEstablished = NetworkUtils.isInternetConnectionEstablished(mockContext);
+        assertFalse(internetConnectionEstablished);
+    }
+
+    @Test
+    public void testInternetConnectionStatusForNullContext() {
+        boolean internetConnectionEstablished = NetworkUtils.isInternetConnectionEstablished(null);
+        assertFalse(internetConnectionEstablished);
+    }
+
+    @Test
+    public void testInternetConnectionForNullConnectivityManager() {
+        Context mockContext = mock(Context.class);
+        Application mockApplication = mock(Application.class);
+        when(mockApplication.getSystemService(Context.CONNECTIVITY_SERVICE))
+                .thenReturn(null);
+        when(mockContext.getApplicationContext()).thenReturn(mockApplication);
+        boolean internetConnectionEstablished = NetworkUtils.isInternetConnectionEstablished(mockContext);
+        assertFalse(internetConnectionEstablished);
+    }
+}