Fixing Azure#210 (Improve binding error message)

kristianhald · Oct 20, 2015 · 84faf32 · 84faf32
1 parent 9ab2199
commit 84faf32
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Showing 2 changed files with 32 additions and 1 deletion.
diff --git a/src/Microsoft.Azure.WebJobs.Host/Bindings/BindingDataProvider.cs b/src/Microsoft.Azure.WebJobs.Host/Bindings/BindingDataProvider.cs
@@ -81,6 +81,11 @@ public IReadOnlyDictionary<string, object> GetBindingData(object value)
         /// <returns>A <see cref="BindingDataProvider"/> instance or null for unsupported types.</returns>
         public static BindingDataProvider FromType(Type type)
         {
+            if (type == null)
+            {
+                throw new ArgumentNullException("type");
+            }
+
             if ((type == typeof(object)) ||
                 (type == typeof(string)) ||
                 (type == typeof(byte[])))
@@ -99,6 +104,12 @@ public static BindingDataProvider FromType(Type type)
             Dictionary<string, Type> contract = new Dictionary<string, Type>(StringComparer.OrdinalIgnoreCase);
             foreach (PropertyHelper property in bindingDataProperties)
             {
+                if (contract.ContainsKey(property.Name))
+                {
+                    throw new InvalidOperationException(
+                        string.Format(CultureInfo.InvariantCulture, 
+                        "Multiple properties named '{0}' found in type '{1}'.", property.Name, type.Name));
+                }
                 contract.Add(property.Name, property.PropertyType);
             }
 

diff --git a/test/Microsoft.Azure.WebJobs.Host.UnitTests/Bindings/BindingDataProviderTests.cs b/test/Microsoft.Azure.WebJobs.Host.UnitTests/Bindings/BindingDataProviderTests.cs
@@ -49,6 +49,16 @@ public void FromType_IfStructuredDataType_ReturnsValidContract()
             Assert.Equal(expected, names);
         }
 
+        [Fact]
+        public void FromType_DuplicatePropertiesDetected_Throws()
+        {
+            var ex = Assert.Throws<InvalidOperationException>(() =>
+            {
+                BindingDataProvider.FromType(typeof(DerivedWithNew));
+            });
+            Assert.Equal("Multiple properties named 'A' found in type 'DerivedWithNew'.", ex.Message);
+        }
+
         [Fact]
         public void GetBindingData_IfSimpleDataType_ReturnsValidBindingData()
         {
@@ -135,7 +145,7 @@ private class DataTypeWithDateProperty
             public DateTime date { get; set; }
         }
 
-        class NestedDataType
+        private class NestedDataType
         {
             public int _field = 0; // skip: not a property
 
@@ -149,5 +159,15 @@ class NestedDataType
 
             private int PrivateIntProp { get; set; } // skip: private property
         }
+
+        private class Base
+        {
+            public int? A { get; set; }
+        }
+
+        private class DerivedWithNew : Base
+        {
+            new public int A { get; set; }
+        }
     }
 }