Add tests for Result#call implementations

spec/errored_result_spec.cr

@@ -15,6 +15,21 @@ def new_errored_result(
 end
 
 describe Spectator::ErroredResult do
+  describe "#call" do
+    it "invokes #error on an instance" do
+      spy = ResultCallSpy.new
+      new_errored_result.call(spy)
+      spy.error?.should be_truthy
+    end
+
+    it "passes itself" do
+      spy = ResultCallSpy.new
+      result = new_errored_result
+      result.call(spy)
+      spy.error.should eq(result)
+    end
+  end
+
   describe "#example" do
     it "is the expected value" do
       example = FailingExample.create

spec/failed_result_spec.cr

@@ -15,6 +15,21 @@ def new_failed_result(
 end
 
 describe Spectator::FailedResult do
+  describe "#call" do
+    it "invokes #failure on an instance" do
+      spy = ResultCallSpy.new
+      new_failed_result.call(spy)
+      spy.failure?.should be_truthy
+    end
+
+    it "passes itself" do
+      spy = ResultCallSpy.new
+      result = new_failed_result
+      result.call(spy)
+      spy.failure.should eq(result)
+    end
+  end
+
   describe "#example" do
     it "is the expected value" do
       example = FailingExample.create

spec/helpers/result_call_spy.cr

@@ -0,0 +1,10 @@
+# Spy class for testing `Spectator::Result#call`.
+class ResultCallSpy
+  {% for name in %i[success failure error pending] %}
+  getter! {{name.id}} : ::Spectator::Result
+
+  def {{name.id}}(arg)
+    @{{name.id}} = arg
+  end
+  {% end %}
+end

spec/pending_result_spec.cr

@@ -5,6 +5,21 @@ def new_pending_result(example : Spectator::Example? = nil)
 end
 
 describe Spectator::PendingResult do
+  describe "#call" do
+    it "invokes #pending on an instance" do
+      spy = ResultCallSpy.new
+      new_pending_result.call(spy)
+      spy.pending?.should be_truthy
+    end
+
+    it "passes itself" do
+      spy = ResultCallSpy.new
+      result = new_pending_result
+      result.call(spy)
+      spy.pending.should eq(result)
+    end
+  end
+
   describe "#example" do
     it "is the expected value" do
       example = PassingExample.create

spec/successful_result_spec.cr

@@ -13,6 +13,21 @@ def new_successful_result(
 end
 
 describe Spectator::SuccessfulResult do
+  describe "#call" do
+    it "invokes #success on an instance" do
+      spy = ResultCallSpy.new
+      new_successful_result.call(spy)
+      spy.success?.should be_truthy
+    end
+
+    it "passes itself" do
+      spy = ResultCallSpy.new
+      result = new_successful_result
+      result.call(spy)
+      spy.success.should eq(result)
+    end
+  end
+
   describe "#example" do
     it "is the expected value" do
       example = PassingExample.create