non-working naive patch to get chai to tell mocha to do a string diff on assertion failures

chai-showDiff.patch

diff --git a/chai.js b/chai.js
index 040abee..87971a8 100644
--- a/chai.js
+++ b/chai.js
@@ -277,6 +277,7 @@
       this.actual = options.actual;
       this.expected = options.expected;
       this.operator = options.operator;
+      this.showDiff = true;
 
       if (options.stackStartFunction && Error.captureStackTrace) {
         var stackStartFunction = options.stackStartFunction;
diff --git a/lib/chai/browser/error.js b/lib/chai/browser/error.js
index c0ac239..d8bcbff 100644
--- a/lib/chai/browser/error.js
+++ b/lib/chai/browser/error.js
@@ -12,6 +12,7 @@ function AssertionError (options) {
   this.actual = options.actual;
   this.expected = options.expected;
   this.operator = options.operator;
+  this.showDiff = true;
 
   if (options.stackStartFunction && Error.captureStackTrace) {
     var stackStartFunction = options.stackStartFunction;
diff --git a/lib/chai/error.js b/lib/chai/error.js
index e3c2fcc..22b69cf 100644
--- a/lib/chai/error.js
+++ b/lib/chai/error.js
@@ -33,6 +33,7 @@ function AssertionError (options) {
   this.actual = options.actual;
   this.expected = options.expected;
   this.operator = options.operator;
+  this.showDiff = true;
 
   if (options.stackStartFunction && Error.captureStackTrace) {
     var stackStartFunction = options.stackStartFunction;