diff --git a/src/main/java/swiss/fihlon/apus/plugin/social/SocialService.java b/src/main/java/swiss/fihlon/apus/plugin/social/SocialService.java
index b677379..7809f94 100644
--- a/src/main/java/swiss/fihlon/apus/plugin/social/SocialService.java
+++ b/src/main/java/swiss/fihlon/apus/plugin/social/SocialService.java
@@ -25,7 +25,6 @@
 import org.springframework.scheduling.TaskScheduler;
 import org.springframework.stereotype.Service;
 import swiss.fihlon.apus.configuration.Configuration;
-import swiss.fihlon.apus.plugin.social.mastodon.MastodonPlugin;
 import swiss.fihlon.apus.social.Post;
 import swiss.fihlon.apus.util.HtmlUtil;
 
@@ -59,8 +58,9 @@ public final class SocialService {
     private List<Post> posts = List.of();
 
     public SocialService(@NotNull final TaskScheduler taskScheduler,
-                         @NotNull final Configuration configuration) {
-        socialPlugin = new MastodonPlugin(configuration);
+                         @NotNull final Configuration configuration,
+                         @NotNull final SocialPlugin socialPlugin) {
+        this.socialPlugin = socialPlugin;
         filterLength = configuration.getFilter().length();
         filterReplies = configuration.getFilter().replies();
         filterSensitive = configuration.getFilter().sensitive();
diff --git a/src/main/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPlugin.java b/src/main/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPlugin.java
index aa4d96a..611a93f 100644
--- a/src/main/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPlugin.java
+++ b/src/main/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPlugin.java
@@ -20,6 +20,7 @@
 import org.jetbrains.annotations.NotNull;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Service;
 import social.bigbone.MastodonClient;
 import social.bigbone.api.Pageable;
 import social.bigbone.api.Range;
@@ -38,6 +39,7 @@
 
 import static social.bigbone.api.method.TimelineMethods.StatusOrigin.LOCAL_AND_REMOTE;
 
+@Service
 public final class MastodonPlugin implements SocialPlugin {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(MastodonPlugin.class);
@@ -57,7 +59,7 @@ public MastodonPlugin(@NotNull final Configuration configuration) {
 
     @Override
     public boolean isEnabled() {
-        return instance != null && !instance.isEmpty() && hashtag != null && !hashtag.isEmpty();
+        return instance != null && !instance.isBlank() && hashtag != null && !hashtag.isBlank();
     }
 
     @Override
diff --git a/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonConfigTest.java b/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonConfigTest.java
index e1bb87e..2ed0ecb 100644
--- a/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonConfigTest.java
+++ b/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonConfigTest.java
@@ -36,8 +36,8 @@ class MastodonConfigTest {
     void testMastodonConfig() {
         final var mastodonConfig = configuration.getMastodon();
         assertNotNull(mastodonConfig);
-        assertEquals("mastodon.social", mastodonConfig.instance());
-        assertEquals("java", mastodonConfig.hashtag());
+        assertEquals("localhost", mastodonConfig.instance());
+        assertEquals("foobar", mastodonConfig.hashtag());
         assertTrue(mastodonConfig.imagesEnabled());
         assertEquals(1, mastodonConfig.imageLimit());
     }
diff --git a/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPluginTest.java b/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPluginTest.java
index dca5c9c..41514f6 100644
--- a/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPluginTest.java
+++ b/src/test/java/swiss/fihlon/apus/plugin/social/mastodon/MastodonPluginTest.java
@@ -18,25 +18,62 @@
 package swiss.fihlon.apus.plugin.social.mastodon;
 
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.extension.ExtendWith;
-import org.mockito.Mock;
-import org.mockito.junit.jupiter.MockitoExtension;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
 import swiss.fihlon.apus.configuration.Configuration;
 import swiss.fihlon.apus.social.Post;
 
 import java.util.List;
+import java.util.stream.Stream;
 
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
-@ExtendWith(MockitoExtension.class)
 class MastodonPluginTest {
 
-    @Mock
-    private Configuration configuration;
+    private static Stream<Arguments> provideDisabledData() {
+        return Stream.of(
+                Arguments.of("", ""),
+                Arguments.of(" ", " "),
+                Arguments.of("", "foobar"),
+                Arguments.of(" ", "foobar"),
+                Arguments.of("localhost", ""),
+                Arguments.of("localhost", " ")
+        );
+    }
+
+    @ParameterizedTest
+    @MethodSource("provideDisabledData")
+    void isDisabled(final String instance, final String hashtag) {
+        final var configuration = mock(Configuration.class);
+        final var mastodonConfig = mock(MastodonConfig.class);
+        when(configuration.getMastodon()).thenReturn(mastodonConfig);
+        when(mastodonConfig.instance()).thenReturn(instance);
+        when(mastodonConfig.hashtag()).thenReturn(hashtag);
+
+        final var mastodonPlugin = new MastodonPlugin(configuration);
+        assertFalse(mastodonPlugin.isEnabled());
+    }
+
+    @Test
+    void isEnabled() {
+        final var configuration = mock(Configuration.class);
+        final var mastodonConfig = mock(MastodonConfig.class);
+        when(configuration.getMastodon()).thenReturn(mastodonConfig);
+        when(mastodonConfig.instance()).thenReturn("localhost");
+        when(mastodonConfig.hashtag()).thenReturn("foobar");
+
+        final var mastodonPlugin = new MastodonPlugin(configuration);
+        assertTrue(mastodonPlugin.isEnabled());
+    }
 
     @Test
     void getPosts() {
+        final var configuration = mock(Configuration.class);
         when(configuration.getMastodon()).thenReturn(
                 new MastodonConfig("mastodon.social", "java", true, 0));
 
diff --git a/src/test/resources/application.properties b/src/test/resources/application.properties
index 1f8eb81..932495d 100644
--- a/src/test/resources/application.properties
+++ b/src/test/resources/application.properties
@@ -6,7 +6,7 @@ apus.filter.sensitive=true
 apus.filter.words=foo, bar, foobar, barfoo
 apus.doag.eventId=-1
 apus.doag.eventApi=file:src/test/resources/DOAG.json?eventId=%d
-apus.mastodon.instance=mastodon.social
-apus.mastodon.hashtag=java
+apus.mastodon.instance=localhost
+apus.mastodon.hashtag=foobar
 apus.mastodon.imagesEnabled=true
 apus.mastodon.imageLimit=1