Add tests for capacity of new arrays.

Author: aardvark179

spec/truffle/array/new_spec.rb

@@ -0,0 +1,39 @@
+# Copyright (c) 2018 Oracle and/or its affiliates. All rights reserved. This
+# code is released under a tri EPL/GPL/LGPL license. You can use it,
+# redistribute it and/or modify it under the terms of the:
+#
+# Eclipse Public License version 1.0, or
+# GNU General Public License version 2, or
+# GNU Lesser General Public License version 2.1.
+
+require_relative '../../ruby/spec_helper'
+
+describe "Array.new" do
+  def storage(ary)
+    Truffle::Debug.array_storage(ary)
+  end
+
+  def capacity(ary)
+    Truffle::Debug.array_capacity(ary)
+  end
+
+  before :each do
+    @long = 1 << 52
+  end
+
+  it "creates arrays with the requested capacity" do
+    a = Array.new(17)
+    capacity(a).should == 17
+  end
+
+  it "creates arrays with the requested capacity with a default value" do
+    a = Array.new(17, 1)
+    capacity(a).should == 17
+  end
+
+  it "creates arrays with the requested capacity with a value block" do
+    a = Array.new(17) { 1 }
+    capacity(a).should == 17    
+  end
+end
+

src/main/java/org/truffleruby/debug/TruffleDebugNodes.java

@@ -295,6 +295,17 @@ public DynamicObject arrayStorage(DynamicObject array) {
 
     }
 
+    @CoreMethod(names = "array_capacity", onSingleton = true, required = 1)
+    public abstract static class ArrayCapacityNode extends CoreMethodArrayArgumentsNode {
+
+        @TruffleBoundary
+        @Specialization(guards = "isRubyArray(array)")
+        public int arrayStorage(DynamicObject array) {
+            return ArrayStrategy.of(array).capacityNode().execute(Layouts.ARRAY.getStore(array));
+        }
+
+    }
+
     @CoreMethod(names = "hash_storage", onSingleton = true, required = 1)
     public abstract static class HashStorageNode extends CoreMethodArrayArgumentsNode {