1 files changed, 20 insertions, 0 deletions
diff --git a/spec/mspec/lib/mspec/matchers/be_nan.rb b/spec/mspec/lib/mspec/matchers/be_nan.rb
new file mode 100644
index 0000000000..aa19391211
--- /dev/null
+++ b/spec/mspec/lib/mspec/matchers/be_nan.rb
@@ -0,0 +1,20 @@
+class BeNaNMatcher
+  def matches?(actual)
+    @actual = actual
+    @actual.kind_of?(Float) && @actual.nan?
+  end
+
+  def failure_message
+    ["Expected #{@actual}", "to be NaN"]
+  end
+
+  def negative_failure_message
+    ["Expected #{@actual}", "not to be NaN"]
+  end
+end
+
+class Object
+  def be_nan
+    BeNaNMatcher.new
+  end
+end