Added some tests

src/main/java/com/mojang/brigadier/tree/ArgumentCommandNode.java

@@ -45,6 +45,10 @@ public class ArgumentCommandNode<S, T> extends CommandNode<S> {
         return type;
     }
 
+    public T getDefaultValue() {
+        return defaultValue;
+    }
+
     @Override
     public String getName() {
         return name;
@@ -110,6 +114,7 @@ public class ArgumentCommandNode<S, T> extends CommandNode<S> {
 
         if (!name.equals(that.name)) return false;
         if (!type.equals(that.type)) return false;
+        if (defaultValue != null ? !defaultValue.equals(that.defaultValue) : that.defaultValue != null) return false;
         return super.equals(o);
     }
 

src/main/java/com/mojang/brigadier/tree/CommandNode.java

@@ -141,7 +141,7 @@ public abstract class CommandNode<S> implements Comparable<CommandNode<S>> {
         if (!children.equals(that.children)) return false;
         if (command != null ? !command.equals(that.command) : that.command != null) return false;
 
-        return true;
+        return isDefaultNode == that.isDefaultNode;
     }
 
     @Override

src/test/java/com/mojang/brigadier/CommandDispatcherTest.java

@@ -15,6 +15,7 @@ import org.mockito.Mock;
 import org.mockito.runners.MockitoJUnitRunner;
 
 import static com.mojang.brigadier.arguments.IntegerArgumentType.integer;
+import static com.mojang.brigadier.builder.LiteralArgumentBuilder.defaultLiteral;
 import static com.mojang.brigadier.builder.LiteralArgumentBuilder.literal;
 import static com.mojang.brigadier.builder.RequiredArgumentBuilder.argument;
 import static org.hamcrest.Matchers.equalTo;
@@ -70,6 +71,15 @@ public class CommandDispatcherTest {
         verify(command).run(any(CommandContext.class));
     }
 
+    @SuppressWarnings("unchecked")
+    @Test
+    public void testCreateAndExecuteDefaultCommand() throws Exception {
+        subject.register(literal("foo").then(defaultLiteral("bar").executes(command)));
+
+        assertThat(subject.execute("foo", source), is(42));
+        verify(command).run(any(CommandContext.class));
+    }
+
     @SuppressWarnings("unchecked")
     @Test
     public void testCreateAndMergeCommands() throws Exception {

src/test/java/com/mojang/brigadier/builder/LiteralArgumentBuilderTest.java

@@ -31,6 +31,7 @@ public class LiteralArgumentBuilderTest {
         final LiteralCommandNode<Object> node = builder.build();
 
         assertThat(node.getLiteral(), is("foo"));
+        assertThat(node.isDefaultNode(), is(false));
     }
 
     @Test

src/test/java/com/mojang/brigadier/builder/RequiredArgumentBuilderTest.java

@@ -14,6 +14,7 @@ import org.mockito.runners.MockitoJUnitRunner;
 
 import static com.mojang.brigadier.arguments.IntegerArgumentType.integer;
 import static com.mojang.brigadier.builder.RequiredArgumentBuilder.argument;
+import static com.mojang.brigadier.builder.RequiredArgumentBuilder.defaultArgument;
 import static org.hamcrest.Matchers.hasSize;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
@@ -38,6 +39,17 @@ public class RequiredArgumentBuilderTest {
 
         assertThat(node.getName(), is("foo"));
         assertThat(node.getType(), is(type));
+        assertThat(node.isDefaultNode(), is(false));
+    }
+
+    @Test
+    public void testBuildDefaultNode() throws Exception {
+        final ArgumentCommandNode<Object, Integer> node = defaultArgument("foo", type, 42).build();
+
+        assertThat(node.getName(), is("foo"));
+        assertThat(node.getType(), is(type));
+        assertThat(node.isDefaultNode(), is(true));
+        assertThat(node.getDefaultValue(), is(42));
     }
 
     @Test

src/test/java/com/mojang/brigadier/tree/ArgumentCommandNodeTest.java

@@ -16,6 +16,7 @@ import org.junit.Test;
 
 import static com.mojang.brigadier.arguments.IntegerArgumentType.integer;
 import static com.mojang.brigadier.builder.RequiredArgumentBuilder.argument;
+import static com.mojang.brigadier.builder.RequiredArgumentBuilder.defaultArgument;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
 import static org.mockito.Mockito.mock;
@@ -44,6 +45,16 @@ public class ArgumentCommandNodeTest extends CommandNodeTest {
         assertThat(contextBuilder.getArguments().get("foo").getResult(), is(123));
     }
 
+    @Test
+    public void testParseDefaultNode() throws Exception {
+        final StringReader reader = new StringReader("");
+        final ArgumentCommandNode<Object, Integer> node = defaultArgument("foo", integer(), 42).build();
+        node.parse(reader, contextBuilder);
+
+        assertThat(contextBuilder.getArguments().containsKey("foo"), is(true));
+        assertThat(contextBuilder.getArguments().get("foo").getResult(), is(42));
+    }
+
     @Test
     public void testUsage() throws Exception {
         assertThat(node.getUsageText(), is("<foo>"));