Add null pointer check to FunctionProperty::value.

Also updates the unit test to test for this behaviour. Refs #7004

Code/Mantid/Framework/API/src/FunctionProperty.cpp

@@ -62,7 +62,8 @@ namespace API
   */
   std::string FunctionProperty::value() const
   {
-    return m_value->asString();
+    if(m_value) return m_value->asString();
+    else return getDefault();
   }
 
   /** Get the value the property was initialised with -its default value
@@ -99,7 +100,7 @@ namespace API
   */
   std::string FunctionProperty::isValid() const 
   {
-    return isDefault() ? "Funcion is empty." : "";
+    return isDefault() ? "Function is empty." : "";
   }
 
   /** Indicates if the function has not been created yet.

Code/Mantid/Framework/API/test/FunctionPropertyTest.h

@@ -41,6 +41,8 @@ public:
   void testValue()
   {
     FunctionProperty prop("fun");
+    TS_ASSERT_EQUALS("", prop.value());
+
     std::string error;
     TS_ASSERT_THROWS_NOTHING(error = prop.setValue("name=FunctionPropertyTest_Function,A=3"));
     TS_ASSERT(error.empty());

Code/Mantid/Framework/PythonInterface/test/python/mantid/api/FunctionPropertyTest.py

@@ -30,6 +30,11 @@ class FunctionPropertyTest(unittest.TestCase):
         func = FunctionProperty("fun")
         self.assertEqual("Function", func.type)
 
+    def test_value_is_empty_string_for_default_property(self):
+        func = FunctionProperty("name")
+        self.assertEquals(None, func.value)
+        self.assertEquals("", func.valueAsStr)
+
     def test_valid_string_value_gives_function_object_as_value(self):
         alg=self.TestFunctionPropAlg()
         alg.initialize()