Check for null before invoking handlers. Also add unit test to validate that handlers can be null.

Resolves #121

Author: Jericho

Source/HttpMultipartParser.UnitTests/StreamingMultipartFormDataParserUnitTests.cs

@@ -0,0 +1,58 @@
+using System.IO;
+using System.Text;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace HttpMultipartParser.UnitTests
+{
+	/// <summary>
+	///     Unit tests for StreamingMultipartFormDataParser.
+	/// </summary>
+	public class StreamingMultipartFormDataParserUnitTests
+	{
+		private static readonly string _testData = TestUtil.TrimAllLines(
+			@"--boundary
+            Content-Disposition: form-data; name=""parameter1""
+
+            This is a sample parameter
+            --boundary
+            Content-Disposition: form-data; name=""file1""; filename=""file1.txt""
+            Content-Type: text/plain
+
+            This is the content of a sample file
+            --boundary--"
+		);
+
+		[Fact]
+		public void CanHandleNullDelegates()
+		{
+			using (Stream stream = TestUtil.StringToStream(_testData, Encoding.UTF8))
+			{
+				var parser = new StreamingMultipartFormDataParser(stream);
+
+				// Intentionally setting these handlers to null to verify that we can parse the stream despite missing handlers
+				// See: https://github.com/Http-Multipart-Data-Parser/Http-Multipart-Data-Parser/issues/121
+				parser.ParameterHandler = null;
+				parser.FileHandler = null;
+
+				parser.Run();
+			}
+		}
+
+		[Fact]
+		public async Task CanHandleNullDelegatesAsync()
+		{
+			using (Stream stream = TestUtil.StringToStream(_testData, Encoding.UTF8))
+			{
+				var parser = new StreamingMultipartFormDataParser(stream);
+
+				// Intentionally setting these handlers to null to verify that we can parse the stream despite missing handlers
+				// See: https://github.com/Http-Multipart-Data-Parser/Http-Multipart-Data-Parser/issues/121
+				parser.ParameterHandler = null;
+				parser.FileHandler = null;
+
+				await parser.RunAsync();
+			}
+		}
+	}
+}

Source/HttpMultipartParser/StreamingBinaryMultipartFormDataParser.cs

@@ -686,7 +686,7 @@ private void ParseFilePart(Dictionary<string, string> parameters, RebufferableBi
 					// We also want to chop off the newline that is inserted by the protocol.
 					// We can do this by reducing endPos by the length of newline in this environment
 					// and encoding
-					FileHandler(name, filename, contentType, contentDisposition, fullBuffer, endPos - bufferNewlineLength, partNumber++, additionalParameters);
+					FileHandler?.Invoke(name, filename, contentType, contentDisposition, fullBuffer, endPos - bufferNewlineLength, partNumber++, additionalParameters);
 
 					int writeBackOffset = endPos + endPosLength + boundaryNewlineOffset;
 					int writeBackAmount = (prevLength + curLength) - writeBackOffset;
@@ -696,7 +696,7 @@ private void ParseFilePart(Dictionary<string, string> parameters, RebufferableBi
 				}
 
 				// No end, consume the entire previous buffer
-				FileHandler(name, filename, contentType, contentDisposition, prevBuffer, prevLength, partNumber++, additionalParameters);
+				FileHandler?.Invoke(name, filename, contentType, contentDisposition, prevBuffer, prevLength, partNumber++, additionalParameters);
 
 				// Now we want to swap the two buffers, we don't care
 				// what happens to the data from prevBuffer so we set
@@ -843,7 +843,7 @@ private async Task ParseFilePartAsync(Dictionary<string, string> parameters, Reb
 					// We also want to chop off the newline that is inserted by the protocl.
 					// We can do this by reducing endPos by the length of newline in this environment
 					// and encoding
-					FileHandler(name, filename, contentType, contentDisposition, fullBuffer, endPos - bufferNewlineLength, partNumber++, additionalParameters);
+					FileHandler?.Invoke(name, filename, contentType, contentDisposition, fullBuffer, endPos - bufferNewlineLength, partNumber++, additionalParameters);
 
 					int writeBackOffset = endPos + endPosLength + boundaryNewlineOffset;
 					int writeBackAmount = (prevLength + curLength) - writeBackOffset;
@@ -853,7 +853,7 @@ private async Task ParseFilePartAsync(Dictionary<string, string> parameters, Reb
 				}
 
 				// No end, consume the entire previous buffer
-				FileHandler(name, filename, contentType, contentDisposition, prevBuffer, prevLength, partNumber++, additionalParameters);
+				FileHandler?.Invoke(name, filename, contentType, contentDisposition, prevBuffer, prevLength, partNumber++, additionalParameters);
 
 				// Now we want to swap the two buffers, we don't care
 				// what happens to the data from prevBuffer so we set
@@ -898,7 +898,7 @@ private void ParseParameterPart(Dictionary<string, string> parameters, Rebuffera
 			if (line.SequenceEqual(endBoundaryBinary)) readEndBoundary = true;
 
 			var part = new ParameterPartBinary(parameters["name"], data);
-			ParameterHandler(part);
+			ParameterHandler?.Invoke(part);
 		}
 
 		/// <summary>
@@ -933,7 +933,7 @@ private async Task ParseParameterPartAsync(Dictionary<string, string> parameters
 			if (line.SequenceEqual(endBoundaryBinary)) readEndBoundary = true;
 
 			var part = new ParameterPartBinary(parameters["name"], data);
-			ParameterHandler(part);
+			ParameterHandler?.Invoke(part);
 		}
 
 		/// <summary>

Source/HttpMultipartParser/StreamingMultipartFormDataParser.cs

@@ -129,12 +129,12 @@ public void Run()
 			var streamingParser = new StreamingBinaryMultipartFormDataParser(stream, boundary, Encoding, BinaryBufferSize, binaryMimeTypes, ignoreInvalidParts);
 			streamingParser.ParameterHandler += binaryParameterPart =>
 			{
-				ParameterHandler.Invoke(new ParameterPart(binaryParameterPart.Name, binaryParameterPart.ToString(Encoding)));
+				ParameterHandler?.Invoke(new ParameterPart(binaryParameterPart.Name, binaryParameterPart.ToString(Encoding)));
 			};
 
 			streamingParser.FileHandler += (name, fileName, type, disposition, buffer, bytes, partNumber, additionalProperties) =>
 			{
-				FileHandler.Invoke(name, fileName, type, disposition, buffer, bytes, partNumber, additionalProperties);
+				FileHandler?.Invoke(name, fileName, type, disposition, buffer, bytes, partNumber, additionalProperties);
 			};
 
 			streamingParser.Run();
@@ -154,12 +154,12 @@ public async Task RunAsync(CancellationToken cancellationToken = default)
 			var streamingParser = new StreamingBinaryMultipartFormDataParser(stream, boundary, Encoding ?? Constants.DefaultEncoding, BinaryBufferSize, binaryMimeTypes, ignoreInvalidParts);
 			streamingParser.ParameterHandler += binaryParameterPart =>
 			{
-				ParameterHandler.Invoke(new ParameterPart(binaryParameterPart.Name, binaryParameterPart.ToString(Encoding)));
+				ParameterHandler?.Invoke(new ParameterPart(binaryParameterPart.Name, binaryParameterPart.ToString(Encoding)));
 			};
 
 			streamingParser.FileHandler += (name, fileName, type, disposition, buffer, bytes, partNumber, additionalProperties) =>
 			{
-				FileHandler.Invoke(name, fileName, type, disposition, buffer, bytes, partNumber, additionalProperties);
+				FileHandler?.Invoke(name, fileName, type, disposition, buffer, bytes, partNumber, additionalProperties);
 			};
 
 			await streamingParser.RunAsync().ConfigureAwait(false);