Add RSpec have_attributes matcher spec

spec/rspec/expectations/have_attributes_matcher_spec.cr

@@ -0,0 +1,37 @@
+require "../../spec_helper"
+
+# Examples taken from:
+# https://relishapp.com/rspec/rspec-expectations/v/3-8/docs/built-in-matchers/have-attributes-matcher
+# and modified to fit Spectator and Crystal.
+Spectator.describe "`have_attributes` matcher" do
+  context "basic usage" do
+    # Use `record` instead of `Struct.new`.
+    record Person, name : String, age : Int32
+
+    describe Person.new("Jim", 32) do
+      # Changed some syntax for Ruby hashes to Crystal named tuples.
+
+      # Spectator doesn't support helper matchers like `a_string_starting_with` and `a_value <`.
+      # But maybe in the future it will.
+      it { is_expected.to have_attributes(name: "Jim") }
+      # it { is_expected.to have_attributes(name: a_string_starting_with("J") ) }
+      it { is_expected.to have_attributes(age: 32) }
+      # it { is_expected.to have_attributes(age: (a_value > 30) ) }
+      it { is_expected.to have_attributes(name: "Jim", age: 32) }
+      # it { is_expected.to have_attributes(name: a_string_starting_with("J"), age: (a_value > 30) ) }
+      it { is_expected.not_to have_attributes(name: "Bob") }
+      it { is_expected.not_to have_attributes(age: 10) }
+      # it { is_expected.not_to have_attributes(age: (a_value < 30) ) }
+
+      # deliberate failures
+      # TODO: Add support for expected failures.
+      xit { is_expected.to have_attributes(name: "Bob") }
+      xit { is_expected.to have_attributes(name: 10) }
+
+      # fails if any of the attributes don't match
+      xit { is_expected.to have_attributes(name: "Bob", age: 32) }
+      xit { is_expected.to have_attributes(name: "Jim", age: 10) }
+      xit { is_expected.to have_attributes(name: "Bob", age: 10) }
+    end
+  end
+end