Improve the failure messages for the have/has predicate matcher.

- For a case like `foo.should have_some_stuff`, "expected #has_some_stuff? to..." is better than "expected #has_some_stuff?(nil) to...".  The nil is confusing since you didn't pass any arguments.
- For a case like `foo.should have_each_of(:a, 7, "bar")`, "expected #has_each_of?(:a, 7, "bar")" is better than "expected #has_each_of?(:a)".  It's best to include all the arguments rather than just the first one.

Changelog.md

@@ -4,6 +4,7 @@
 
 * Enhancements
   * HaveMatcher converts argument using #to_i (Alex Bepple & Pat Maddox)
+  * Improved failure message for the have_xxx matcher (Myron Marston)
 
 ### 2.6.0 / 2011-05-12
 

features/built_in_matchers/predicates.feature

@@ -101,7 +101,7 @@ Feature: predicate matchers
        """
      When I run `rspec should_not_have_all_string_keys_spec.rb`
      Then the output should contain "2 examples, 1 failure"
-      And the output should contain "expected #has_all_string_keys?(nil) to return false, got true"
+      And the output should contain "expected #has_all_string_keys? to return false, got true"
 
    Scenario: matcher arguments are passed on to the predicate method
      Given a file named "predicate_matcher_argument_spec.rb" with:

lib/rspec/matchers/has.rb

@@ -10,15 +10,15 @@ def matches?(actual)
       end
 
       def failure_message_for_should
-        "expected ##{predicate(@expected)}(#{@args[0].inspect}) to return true, got false"
+        "expected ##{predicate(@expected)}#{failure_message_args_description} to return true, got false"
       end
 
       def failure_message_for_should_not
-        "expected ##{predicate(@expected)}(#{@args[0].inspect}) to return false, got true"
+        "expected ##{predicate(@expected)}#{failure_message_args_description} to return false, got true"
       end
 
       def description
-        [method_description(@expected), args_description(@args)].compact.join(' ')
+        [method_description(@expected), args_description].compact.join(' ')
       end
 
     private
@@ -30,9 +30,14 @@ def method_description(method)
         method.to_s.gsub('_', ' ')
       end
 
-      def args_description(args)
-        return nil if args.empty?
-        args.map { |arg| arg.inspect }.join(', ')
+      def args_description
+        return nil if @args.empty?
+        @args.map { |arg| arg.inspect }.join(', ')
+      end
+
+      def failure_message_args_description
+        desc = args_description
+        "(#{desc})" if desc
       end
     end
   end

spec/rspec/matchers/has_spec.rb

@@ -11,14 +11,30 @@
     }.should fail_with("expected #has_key?(:a) to return true, got false")
   end
 
+  it 'does not include any args in the failure message if no args were given to the matcher' do
+    o = Object.new
+    def o.has_some_stuff?; false; end
+    expect {
+      o.should have_some_stuff
+    }.to fail_with("expected #has_some_stuff? to return true, got false")
+  end
+
+  it 'includes multiple args in the failure message if multiple args were given to the matcher' do
+    o = Object.new
+    def o.has_some_stuff?(*_); false; end
+    expect {
+      o.should have_some_stuff(:a, 7, "foo")
+    }.to fail_with('expected #has_some_stuff?(:a, 7, "foo") to return true, got false')
+  end
+
   it "fails if #has_sym?(*args) returns nil" do
     klass = Class.new do
       def has_foo?
       end
     end
     lambda {
       klass.new.should have_foo
-    }.should fail_with("expected #has_foo?(nil) to return true, got false")
+    }.should fail_with(/expected #has_foo.* to return true, got false/)
   end
 
   it "fails if target does not respond to #has_sym?" do
@@ -68,6 +84,22 @@ def o.has_sym?(*args)
     end
     lambda { o.should_not have_sym(:foo) }.should raise_error("Funky exception")
   end
+
+  it 'does not include any args in the failure message if no args were given to the matcher' do
+    o = Object.new
+    def o.has_some_stuff?; true; end
+    expect {
+      o.should_not have_some_stuff
+    }.to fail_with("expected #has_some_stuff? to return false, got true")
+  end
+
+  it 'includes multiple args in the failure message if multiple args were given to the matcher' do
+    o = Object.new
+    def o.has_some_stuff?(*_); true; end
+    expect {
+      o.should_not have_some_stuff(:a, 7, "foo")
+    }.to fail_with('expected #has_some_stuff?(:a, 7, "foo") to return false, got true')
+  end
 end
 
 describe "has" do