1 files changed, 39 insertions, 4 deletions
diff --git a/spec/ruby/core/struct/to_h_spec.rb b/spec/ruby/core/struct/to_h_spec.rb
index ddfbfbca61..b5f4e40701 100644
--- a/spec/ruby/core/struct/to_h_spec.rb
+++ b/spec/ruby/core/struct/to_h_spec.rb
@@ -14,10 +14,45 @@ describe "Struct#to_h" do
   end
 
   ruby_version_is "2.6" do
-    it "converts [key, value] pairs returned by the block to a hash" do
-      car = StructClasses::Car.new('Ford', 'Ranger')
-      h = car.to_h {|k, v| [k.to_s, "#{v}".downcase]}
-      h.should == {"make" => "ford", "model" => "ranger", "year" => ""}
+    context "with block" do
+      it "converts [key, value] pairs returned by the block to a hash" do
+        car = StructClasses::Car.new('Ford', 'Ranger')
+
+        h = car.to_h { |k, v| [k.to_s, "#{v}".downcase] }
+        h.should == { "make" => "ford", "model" => "ranger", "year" => "" }
+      end
+
+      it "raises ArgumentError if block returns longer or shorter array" do
+        -> do
+          StructClasses::Car.new.to_h { |k, v| [k.to_s, "#{v}".downcase, 1] }
+        end.should raise_error(ArgumentError, /element has wrong array length/)
+
+        -> do
+          StructClasses::Car.new.to_h { |k, v| [k] }
+        end.should raise_error(ArgumentError, /element has wrong array length/)
+      end
+
+      it "raises TypeError if block returns something other than Array" do
+        -> do
+          StructClasses::Car.new.to_h { |k, v| "not-array" }
+        end.should raise_error(TypeError, /wrong element type String/)
+      end
+
+      it "coerces returned pair to Array with #to_ary" do
+        x = mock('x')
+        x.stub!(:to_ary).and_return([:b, 'b'])
+
+        StructClasses::Car.new.to_h { |k| x }.should == { :b => 'b' }
+      end
+
+      it "does not coerce returned pair to Array with #to_a" do
+        x = mock('x')
+        x.stub!(:to_a).and_return([:b, 'b'])
+
+        -> do
+          StructClasses::Car.new.to_h { |k| x }
+        end.should raise_error(TypeError, /wrong element type MockObject/)
+      end
     end
   end
 end