IllegalArgumentException in MethodHelper for function that does not return a CharSequence #606

Author: jknack

handlebars/src/main/java/com/github/jknack/handlebars/helper/DefaultHelperRegistry.java

@@ -206,7 +206,7 @@ private void registerDynamicHelper(final Object source, final Class<?> clazz) {
       for (Method method : methods) {
         boolean isPublic = Modifier.isPublic(method.getModifiers());
         String helperName = method.getName();
-        if (isPublic && CharSequence.class.isAssignableFrom(method.getReturnType())) {
+        if (isPublic) {
           boolean isStatic = Modifier.isStatic(method.getModifiers());
           if (source != null || isStatic) {
             isTrue(overloaded.add(helperName), "name conflict found: " + helperName);

handlebars/src/main/java/com/github/jknack/handlebars/helper/MethodHelper.java

@@ -76,7 +76,7 @@ public Object apply(final Object context, final Options options) throws IOExcept
           }
         }
       }
-      return (CharSequence) method.invoke(source, args);
+      return method.invoke(source, args);
     } catch (ArrayIndexOutOfBoundsException ex) {
       throw new IllegalArgumentException(
           "could not execute helper: " + toString(method) + ", with the given arguments: "

handlebars/src/test/java/com/github/jknack/handlebars/ReflectiveHelperTest.java

@@ -71,7 +71,7 @@ public void testBlogTitle() throws IOException {
   }
 
   @Test
-  public void params() throws IOException {
+  public void testParams() throws IOException {
     shouldCompileTo("{{params this l d f c b s}}",
         $("l", 1L, "d", 2.0D, "f", 3.0f, "c", '4', "b", (byte) 5, "s", (short) 6),
         "1, 2.0, 3.0, 4, 5, 6");

handlebars/src/test/java/com/github/jknack/handlebars/issues/Issue606.java

@@ -0,0 +1,28 @@
+package com.github.jknack.handlebars.issues;
+
+import com.github.jknack.handlebars.Handlebars;
+import com.github.jknack.handlebars.v4Test;
+import org.junit.Test;
+
+import java.util.Arrays;
+
+public class Issue606 extends v4Test {
+
+  public static class Helpers {
+
+    public int subtract(int a, int b) {
+      return a - b;
+    }
+  }
+
+  @Override protected void configure(Handlebars handlebars) {
+    super.configure(handlebars);
+    handlebars.registerHelpers(new Helpers());
+  }
+
+  @Test
+  public void shouldSupportNoneCharSequenceReturnsTypeFromHelperClass() throws Exception {
+    shouldCompileTo("{{#if (subtract value 1)}}OK{{/if}}", $("hash", $("value", 2)), "OK");
+    shouldCompileTo("{{#if (subtract value 1)}}OK{{/if}}", $("hash", $("value", 1)), "");
+  }
+}