1 files changed, 52 insertions, 0 deletions
diff --git a/spec/ruby/core/struct/dig_spec.rb b/spec/ruby/core/struct/dig_spec.rb
new file mode 100644
index 0000000000..93a52dbbe1
--- /dev/null
+++ b/spec/ruby/core/struct/dig_spec.rb
@@ -0,0 +1,52 @@
+require_relative '../../spec_helper'
+
+describe "Struct#dig" do
+  before(:each) do
+    @klass = Struct.new(:a)
+    @instance = @klass.new(@klass.new({ b: [1, 2, 3] }))
+  end
+
+  it "returns the nested value specified by the sequence of keys" do
+    @instance.dig(:a, :a).should == { b: [1, 2, 3] }
+  end
+
+  it "accepts String keys" do
+    @instance.dig('a', 'a').should == { b: [1, 2, 3] }
+  end
+
+  it "returns the value by the index" do
+    instance = Struct.new(:a, :b).new(:one, :two)
+    instance.dig(0).should == :one
+    instance.dig(1).should == :two
+  end
+
+  it "returns the nested value specified if the sequence includes an index" do
+    @instance.dig(:a, :a, :b, 0).should == 1
+  end
+
+  it "returns nil if any intermediate step is nil" do
+    @instance.dig(:b, 0).should == nil
+  end
+
+  it "raises a TypeError if any intermediate step does not respond to #dig" do
+    instance = @klass.new(1)
+    -> {
+      instance.dig(:a, 3)
+    }.should raise_error(TypeError)
+  end
+
+  it "raises an ArgumentError if no arguments provided" do
+    -> { @instance.dig }.should raise_error(ArgumentError)
+  end
+
+  it "calls #dig on any intermediate step with the rest of the sequence as arguments" do
+    obj = Object.new
+    instance = @klass.new(obj)
+
+    def obj.dig(*args)
+      {dug: args}
+    end
+
+    instance.dig(:a, :bar, :baz).should == { dug: [:bar, :baz] }
+  end
+end