Add specs for #dig implmenetation for Hash, Array and Struct classes

Author: ahmadsherif

core/array/dig_spec.rb

@@ -15,18 +15,35 @@
       a.dig(0, -1, 0).should == 2
     end
 
+    it "returns the nested value specified if the sequence includes a key" do
+      a = [42, { foo: :bar }]
+      a.dig(1, :foo).should == :bar
+    end
+
     it "raises a TypeError for a non-numeric index" do
       lambda {
         ['a'].dig(:first)
       }.should raise_error(TypeError)
     end
 
+    it "raises a TypeError if any intermediate step does not respond to #dig" do
+      a = [1, 2]
+      lambda {
+        a.dig(0, 1)
+      }.should raise_error(TypeError)
+    end
+
     it "raises without any args" do
       lambda {
         [10].dig()
       }.should raise_error(ArgumentError)
     end
 
+    it "returns nil if any intermediate step is nil" do
+      a = [[1, [2, 3]]]
+      a.dig(1, 2, 3).should == nil
+    end
+
     it "calls #dig on the result of #at with the remaining arguments" do
       h = [[nil, [nil, nil, 42]]]
       h[0].should_receive(:dig).with(1, 2).and_return(42)

core/hash/dig_spec.rb

@@ -10,14 +10,24 @@
       h.dig(1).should be_nil
     end
 
-    it "does recurse" do
+    it "returns the nested value specified by the sequence of keys" do
       h = { foo: { bar: { baz: 1 } } }
       h.dig(:foo, :bar, :baz).should == 1
       h.dig(:foo, :bar, :nope).should be_nil
       h.dig(:foo, :baz).should be_nil
       h.dig(:bar, :baz, :foo).should be_nil
     end
 
+    it "returns the nested value specified if the sequence includes an index" do
+      h = { foo: [1, 2, 3] }
+      h.dig(:foo, 2).should == 3
+    end
+
+    it "returns nil if any intermediate step is nil" do
+      h = { foo: { bar: { baz: 1 } } }
+      h.dig(:foo, :zot, :xyz).should == nil
+    end
+
     it "raises without args" do
       lambda { { the: 'borg' }.dig() }.should raise_error(ArgumentError)
     end
@@ -47,6 +57,5 @@ def obj.dig(*args); [ 42 ] end
       h[:foo].should_receive(:dig).with(:bar, :baz).and_return(42)
       h.dig(:foo, :bar, :baz).should == 42
     end
-
   end
 end

core/struct/dig_spec.rb

@@ -0,0 +1,38 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+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 "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)
+    lambda {
+      instance.dig(:a, 3)
+    }.should raise_error(TypeError)
+  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