Display error properties for failed specs

spec/core/ExceptionFormatterSpec.js

@@ -116,5 +116,27 @@ describe("ExceptionFormatter", function() {
     it("returns null if no Error provided", function() {
       expect(new jasmineUnderTest.ExceptionFormatter().stack()).toBeNull();
     });
+
+    it("includes error properties in stack", function() {
+      var error;
+      try { throw new Error("an error") } catch(e) { error = e; }
+      error.someProperty = 'hello there';
+
+      var result = new jasmineUnderTest.ExceptionFormatter().stack(error);
+
+      expect(result).toMatch(/error properties: {/);
+      expect(result).toMatch(/"someProperty": "hello there"/);
+    });
+
+    it("drops error properties if there is a cycle", function() {
+      var error;
+      try { throw new Error("an error") } catch(e) { error = e; }
+      error.someProperty = error;
+
+      var result = new jasmineUnderTest.ExceptionFormatter().stack(error);
+
+      expect(result).not.toMatch(/error properties/);
+    });
+
   });
 });

src/core/ExceptionFormatter.js

@@ -29,12 +29,16 @@ getJasmineRequireObj().ExceptionFormatter = function(j$) {
 
       var stackTrace = new j$.StackTrace(error.stack);
       var lines = filterJasmine(stackTrace);
+      var result = '';
 
       if (stackTrace.message) {
         lines.unshift(stackTrace.message);
       }
 
-      return lines.join('\n');
+      result += formatProperties(error);
+      result += lines.join('\n');
+
+      return result;
     };
 
     function filterJasmine(stackTrace) {
@@ -51,6 +55,32 @@ getJasmineRequireObj().ExceptionFormatter = function(j$) {
  
       return result;
     }
+
+    function formatProperties(error) {
+      if (!(error instanceof Object)) {
+        return;
+      }
+
+      var ignored = ['name', 'message', 'stack', 'fileName', 'sourceURL', 'line', 'lineNumber', 'stack'];
+      var result = {};
+      var empty = true;
+
+      for (var prop in error) {
+        if (ignored.includes(prop)) {
+          continue;
+        }
+        result[prop] = error[prop];
+        empty = false;
+      }
+
+      if (!empty) {
+        try {
+          return 'error properties: ' + JSON.stringify(result, null, 2) + '\n';
+        } catch (_) {}
+      }
+
+      return '';
+    }
   }
 
   return ExceptionFormatter;