1 files changed, 71 insertions, 0 deletions
diff --git a/spec/mspec/lib/mspec/matchers/output_to_fd.rb b/spec/mspec/lib/mspec/matchers/output_to_fd.rb
new file mode 100644
index 0000000000..5daaf5545c
--- /dev/null
+++ b/spec/mspec/lib/mspec/matchers/output_to_fd.rb
@@ -0,0 +1,71 @@
+require 'mspec/helpers/tmp'
+
+# Lower-level output speccing mechanism for a single
+# output stream. Unlike OutputMatcher which provides
+# methods to capture the output, we actually replace
+# the FD itself so that there is no reliance on a
+# certain method being used.
+class OutputToFDMatcher
+  def initialize(expected, to)
+    @to, @expected = to, expected
+
+    case @to
+    when STDOUT
+      @to_name = "STDOUT"
+    when STDERR
+      @to_name = "STDERR"
+    when IO
+      @to_name = @to.object_id.to_s
+    else
+      raise ArgumentError, "#{@to.inspect} is not a supported output target"
+    end
+  end
+
+  def with_tmp
+    path = tmp("mspec_output_to_#{$$}_#{Time.now.to_i}")
+    File.open(path, 'w+') { |io|
+      yield(io)
+    }
+  ensure
+    File.delete path if path
+  end
+
+  def matches?(block)
+    old_to = @to.dup
+    with_tmp do |out|
+      # Replacing with a file handle so that Readline etc. work
+      @to.reopen out
+      begin
+        block.call
+      ensure
+        @to.reopen old_to
+        old_to.close
+      end
+
+      out.rewind
+      @actual = out.read
+
+      case @expected
+      when Regexp
+        !(@actual =~ @expected).nil?
+      else
+        @actual == @expected
+      end
+    end
+  end
+
+  def failure_message()
+    ["Expected (#{@to_name}): #{@expected.inspect}\n",
+     "#{'but got'.rjust(@to_name.length + 10)}: #{@actual.inspect}\nBacktrace"]
+  end
+
+  def negative_failure_message()
+    ["Expected output (#{@to_name}) to NOT be:\n", @actual.inspect]
+  end
+end
+
+class Object
+  def output_to_fd(what, where = STDOUT)
+    OutputToFDMatcher.new what, where
+  end
+end