Deprecate usage of should_not raise_error

lib/mspec/expectations/should.rb

@@ -23,6 +23,10 @@ def should_not(matcher = NO_MATCHER_GIVEN)
     raise "should_not outside example" unless state
     MSpec.actions :expectation, state
 
+    if RaiseErrorMatcher === matcher
+      MSpec.deprecate('->{}.should_not raise_error', 'a matcher to verify the result')
+    end
+
     if NO_MATCHER_GIVEN.equal?(matcher)
       SpecNegativeOperatorMatcher.new(self)
     else

spec/expectations/should.rb

@@ -70,4 +70,8 @@ def finish
   it "invokes the MSpec :expectation actions" do
     1.should_not == 2
   end
+
+  it "deprecates using `{}.should_not raise_error`" do
+    -> { }.should_not raise_error
+  end
 end

spec/expectations/should_spec.rb

@@ -6,7 +6,7 @@
     path = RbConfig::CONFIG['bindir']
     exe  = RbConfig::CONFIG['ruby_install_name']
     file = File.dirname(__FILE__) + '/should.rb'
-    @out = `#{path}/#{exe} #{file}`
+    @out = `#{path}/#{exe} #{file} 2>&1`
   end
 
   describe "#should" do
@@ -45,17 +45,22 @@
 No behavior expectation was found in the example
 EOS
     end
+
+    it 'prints a deprecation message about using `{}.should_not raise_error`' do
+      @out.should include "->{}.should_not raise_error is deprecated, use a matcher to verify the result instead."
+      @out.should =~ /from .+spec\/expectations\/should.rb:75:in `block \(2 levels\) in <main>'/
+    end
   end
 
   it "prints status information" do
     @out.should include ".FF..FF."
   end
 
   it "prints out a summary" do
-    @out.should include "0 files, 8 examples, 6 expectations, 4 failures, 0 errors"
+    @out.should include "0 files, 9 examples, 7 expectations, 4 failures, 0 errors"
   end
 
   it "records expectations" do
-    @out.should include "I was called 6 times"
+    @out.should include "I was called 7 times"
   end
 end