avoid servlet/filter postfix cut for short names during name generation

src/main/java/ru/vyarus/dropwizard/guice/module/installer/feature/web/util/WebUtils.java

@@ -25,7 +25,7 @@ private WebUtils() {
      * For example, for class "MyCoolFilter" generated name will be ".mycool".
      *
      * @param filter filter annotation
-     * @param type filter type
+     * @param type   filter type
      * @return filter name or generated name if name not provided
      */
     public static String getFilterName(final WebFilter filter, final Class<? extends Filter> type) {
@@ -34,9 +34,8 @@ public static String getFilterName(final WebFilter filter, final Class<? extends
     }
 
     /**
-     *
      * @param servlet servlet annotation
-     * @param type servlet type
+     * @param type    servlet type
      * @return servlet name or generated name if name not provided
      */
     public static String getServletName(final WebServlet servlet, final Class<? extends HttpServlet> type) {
@@ -101,8 +100,10 @@ private static String getAsyncMarker(final boolean async) {
 
     private static String generateName(final Class<?> type, final String keyword) {
         String probe = '.' + type.getSimpleName().toLowerCase();
-        if (probe.endsWith(keyword)) {
-            probe = probe.substring(0, probe.length() - keyword.length());
+        final int targetLength = probe.length() - keyword.length();
+        // leave prefix if remaining part is too short (and if target name equal prefix)
+        if (probe.endsWith(keyword) && targetLength > 2) {
+            probe = probe.substring(0, targetLength);
         }
         return probe;
     }

src/test/groovy/ru/vyarus/dropwizard/guice/web/ServletGenNameCollisionTest.groovy

@@ -0,0 +1,58 @@
+package ru.vyarus.dropwizard.guice.web
+
+import io.dropwizard.Application
+import io.dropwizard.Configuration
+import io.dropwizard.setup.Bootstrap
+import io.dropwizard.setup.Environment
+import org.eclipse.jetty.servlet.ServletHolder
+import ru.vyarus.dropwizard.guice.GuiceBundle
+import ru.vyarus.dropwizard.guice.test.spock.UseGuiceyApp
+import spock.lang.Specification
+
+import javax.inject.Inject
+import javax.servlet.annotation.WebServlet
+import javax.servlet.http.HttpServlet
+
+
+/**
+ * @author Vyacheslav Rusakov
+ * @since 22.08.2016
+ */
+@UseGuiceyApp(GCollApp)
+class ServletGenNameCollisionTest extends Specification {
+
+    @Inject
+    Environment environment
+
+    def "Check servlet name generation"() {
+
+        expect: "OServlet name without postfix cut"
+        ServletHolder oservlet = environment.getApplicationContext().getServletHandler().getServlet(".oservlet")
+        oservlet.registration.className == OServlet.name
+
+        and: "Servlet name without postfix cut"
+        ServletHolder servlet = environment.getApplicationContext().getServletHandler().getServlet(".servlet")
+        servlet.registration.className == Servlet.name
+    }
+
+    static class GCollApp extends Application<Configuration> {
+        @Override
+        void initialize(Bootstrap<Configuration> bootstrap) {
+            bootstrap.addBundle(GuiceBundle.builder()
+                    .useWebInstallers()
+                    .extensions(OServlet, Servlet)
+                    .build())
+        }
+
+        @Override
+        void run(Configuration configuration, Environment environment) throws Exception {
+
+        }
+    }
+
+    @WebServlet("/foo")
+    static class OServlet extends HttpServlet {}
+
+    @WebServlet("/bar")
+    static class Servlet extends HttpServlet {}
+}