Handle format exceptions and provide some more information.

Author: StringEpsilon

CHANGELOG.md

@@ -1,7 +1,8 @@
 # Future:
 - Improved performance of the validation step of deserialization.
 - Speed up deserializing into explicit types (particularly structs and classes) significantly.
-- Improved exception messages on malformed input when deserializing.
+- Improved exception messages on malformed inputs when deserializing.
+- Cleaner exception when trying to deserialize into incompatible types (i.e. "a" to int32.).
 
 # 0.7.4:
 - Improved deserialization performance.

PhpSerializerNET.Test/Deserialize/Options/EmptyStringToDefault.cs

@@ -29,26 +29,38 @@ public void Enabled_StringToDouble() {
 
 		[TestMethod]
 		public void Disabled_EmptyStringToInt() {
-			var ex = Assert.ThrowsException<System.FormatException>(
+			var exception = Assert.ThrowsException<DeserializationException>(
 				() => PhpSerialization.Deserialize<int>("s:0:\"\";", new PhpDeserializationOptions(){EmptyStringToDefault = false})
 			);
-			// TODO: Rethrow the exception in the code with a useful error message, then test that here.
+			
+			Assert.AreEqual(
+				"Exception encountered while trying to assign '' to type Int32. See inner exception for details.",
+				exception.Message
+			);
 		}
 
 		[TestMethod]
 		public void Disabled_StringToBool() {
-			var ex = Assert.ThrowsException<System.FormatException>(
+			var exception = Assert.ThrowsException<DeserializationException>(
 				() => PhpSerialization.Deserialize<bool>("s:0:\"\";", new PhpDeserializationOptions(){EmptyStringToDefault = false})
 			);
-			// TODO: Rethrow the exception in the code with a useful error message, then test that here.
+			
+			Assert.AreEqual(
+				"Exception encountered while trying to assign '' to type Boolean. See inner exception for details.",
+				exception.Message
+			);
 		}
 
 		[TestMethod]
 		public void Disabled_StringToDouble() {
-			var ex = Assert.ThrowsException<System.FormatException>(
+			var exception = Assert.ThrowsException<DeserializationException>(
 				() => PhpSerialization.Deserialize<double>("s:0:\"\";", new PhpDeserializationOptions(){EmptyStringToDefault = false})
 			);
-			// TODO: Rethrow the exception in the code with a useful error message, then test that here.
+			
+			Assert.AreEqual(
+				"Exception encountered while trying to assign '' to type Double. See inner exception for details.",
+				exception.Message
+			);
 		}
 	}
 }

PhpSerializerNET.Test/Deserialize/Options/NumberStringToBool.cs

@@ -22,14 +22,17 @@ public void Enabled_Deserializes() {
 
 		[TestMethod]
 		public void Disabled_Throws() {
-			var exception = Assert.ThrowsException<System.FormatException>(
+			var exception = Assert.ThrowsException<DeserializationException>(
 				() => PhpSerialization.Deserialize<bool>(
 					"s:1:\"0\";",
 					new PhpDeserializationOptions() { NumberStringToBool = false }
 				)
 			);
 
-			// TODO: Rethrow the format exception and assert the proper text.
+			Assert.AreEqual(
+				"Exception encountered while trying to assign '0' to type Boolean. See inner exception for details.",
+				exception.Message
+			);
 		}
 	}
 }

PhpSerializerNET/PhpDeserializer.cs

@@ -156,7 +156,15 @@ private object DeserializeToken(Type targetType, PhpSerializeToken token) {
 								return token.ToBool();
 							}
 						}
-						return ((IConvertible)token.Value).ToType(targetType, CultureInfo.InvariantCulture);
+						
+						try{
+							return ((IConvertible)token.Value).ToType(targetType, CultureInfo.InvariantCulture);
+						} catch(Exception exception){
+							throw new DeserializationException(
+								$"Exception encountered while trying to assign '{token.Value}' to type {targetType.Name}. See inner exception for details.",
+								exception
+							);
+						}
 					} else if(targetType == typeof(System.Guid)) {
 						return new Guid(token.Value);
 					} else {