Add stream error messages.

lib/protocol/http2/error.rb

@@ -50,6 +50,33 @@ class Error < HTTP::Error
 
 			# The endpoint requires that HTTP/1.1 be used instead of HTTP/2.
 			HTTP_1_1_REQUIRED = 0xD
+
+			MESSAGES = {
+				NO_ERROR => "No error.",
+				PROTOCOL_ERROR => "Protocol error!",
+				INTERNAL_ERROR => "Internal error!",
+				FLOW_CONTROL_ERROR => "Flow control error!",
+				SETTINGS_TIMEOUT => "Settings timeout!",
+				STREAM_CLOSED => "Stream closed!",
+				FRAME_SIZE_ERROR => "Frame size error!",
+				REFUSED_STREAM => "Stream refused.",
+				CANCEL => "Stream cancelled.",
+				COMPRESSION_ERROR => "Compression error!",
+				CONNECT_ERROR => "Connect error!",
+				ENHANCE_YOUR_CALM => "Enhance your calm!",
+				INADEQUATE_SECURITY => "Inadequate security!",
+				HTTP_1_1_REQUIRED => "HTTP/1.1 required.",
+			}
+
+			# Get the message for a given HTTP/2 error code.
+			# @parameter code [Integer] The HTTP/2 error code.
+			# @returns [String] The error message.
+			def self.message_for(code)
+				return MESSAGES.fetch(code) do
+					# Unknown error codes are allowed by the protocol, but don't have a static message.
+					"Unknown code: #{code}!"
+				end
+			end
 		end
 
 		# Raised if connection header is missing or invalid indicating that
@@ -62,6 +89,13 @@ class HandshakeError < Error
 		# which signals termination of the current connection. You *cannot*
 		# recover from this exception, or any exceptions subclassed from it.
 		class ProtocolError < Error
+			# Build a protocol error for a given HTTP/2 error code.
+			# @parameter code [Integer] The HTTP/2 error code.
+			# @returns [ProtocolError] The protocol error.
+			def self.for(code)
+				return self.new(Error.message_for(code), code)
+			end
+
 			# Initialize a protocol error with message and error code.
 			# @parameter message [String] The error message.
 			# @parameter code [Integer] The HTTP/2 error code.

lib/protocol/http2/stream.rb

@@ -253,7 +253,7 @@ def close!(error_code = nil)
 					if error_code == REFUSED_STREAM
 						error = ::Protocol::HTTP::RefusedError.new("Stream refused.")
 					else
-						error = StreamError.new("Stream closed!", error_code)
+						error = StreamError.for(error_code)
 					end
 				end
 

releases.md

@@ -1,5 +1,9 @@
 # Releases
 
+## Unreleased
+
+  - Improve `StreamError` messages for HTTP/2 stream reset error codes.
+
 ## v0.26.0
 
   - On RST\_STREAM with REFUSED\_STREAM, close the stream with `Protocol::HTTP::RefusedError` instead of `StreamError`.

test/protocol/http2/error.rb

@@ -5,6 +5,50 @@
 
 require "protocol/http2/error"
 
+describe Protocol::HTTP2::Error do
+	with ".message_for" do
+		it "returns a static message for a known error code" do
+			expect(subject.message_for(subject::CANCEL)).to be == "Stream cancelled."
+		end
+
+		it "returns a fallback message for an unknown error code" do
+			expect(subject.message_for(99)).to be == "Unknown code: 99!"
+		end
+	end
+end
+
+describe Protocol::HTTP2::ProtocolError do
+	with ".for" do
+		it "builds a protocol error for a known error code" do
+			error = subject.for(subject::PROTOCOL_ERROR)
+
+			expect(error).to be_a(subject)
+			expect(error.message).to be == "Protocol error!"
+			expect(error.code).to be == subject::PROTOCOL_ERROR
+		end
+	end
+end
+
+describe Protocol::HTTP2::StreamError do
+	with ".for" do
+		it "builds a stream error for a known error code" do
+			error = subject.for(Protocol::HTTP2::Error::CANCEL)
+
+			expect(error).to be_a(subject)
+			expect(error.message).to be == "Stream cancelled."
+			expect(error.code).to be == Protocol::HTTP2::Error::CANCEL
+		end
+
+		it "builds a stream error for an unknown error code" do
+			error = subject.for(99)
+
+			expect(error).to be_a(subject)
+			expect(error.message).to be == "Unknown code: 99!"
+			expect(error.code).to be == 99
+		end
+	end
+end
+
 describe Protocol::HTTP2::HeaderError do
 	let(:error) {subject.new("Invalid header key")}