#989 Ensure config comments never exceed 90 chars

- Prevents horizontal scrollbar on markdown page (and in users' editors)
- Add test that each property is accompanied with a comment

src/test/java/fr/xephi/authme/settings/SettingsConsistencyTest.java

@@ -0,0 +1,69 @@
+package fr.xephi.authme.settings;
+
+import com.github.authme.configme.knownproperties.ConfigurationData;
+import com.github.authme.configme.properties.Property;
+import fr.xephi.authme.settings.properties.AuthMeSettingsRetriever;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import static org.junit.Assert.fail;
+
+/**
+ * Tests the consistency of the settings configuration.
+ */
+public class SettingsConsistencyTest {
+
+    /**
+     * Maximum characters one comment line may have (prevents horizontal scrolling).
+     */
+    private static final int MAX_COMMENT_LENGTH = 90;
+
+    private static ConfigurationData configurationData;
+
+    @BeforeClass
+    public static void buildConfigurationData() {
+        configurationData = AuthMeSettingsRetriever.buildConfigurationData();
+    }
+
+    @Test
+    public void shouldHaveCommentOnEachProperty() {
+        // given
+        List<Property<?>> properties = configurationData.getProperties();
+
+        // when / then
+        for (Property<?> property : properties) {
+            if (configurationData.getCommentsForSection(property.getPath()).length == 0) {
+                fail("No comment defined for '" + property + "'");
+            }
+        }
+    }
+
+    @Test
+    public void shouldNotHaveVeryLongCommentLines() {
+        // given
+        List<Property<?>> properties = configurationData.getProperties();
+        List<Property<?>> badProperties = new ArrayList<>();
+
+        // when
+        for (Property<?> property : properties) {
+            for (String comment : configurationData.getCommentsForSection(property.getPath())) {
+                if (comment.length() > MAX_COMMENT_LENGTH) {
+                    badProperties.add(property);
+                    break;
+                }
+            }
+        }
+
+        // then
+        if (!badProperties.isEmpty()) {
+            fail("Comment lines should not be longer than " + MAX_COMMENT_LENGTH + " chars, "
+                + "but found too long comments for:\n- "
+                + badProperties.stream().map(Property::getPath).collect(Collectors.joining("\n- ")));
+        }
+    }
+
+}