From d76627fbab6991a02ff7fe4fefc653f105b62190 Mon Sep 17 00:00:00 2001
From: Patrik Wenger <patrik.wenger@mindclue.ch>
Date: Mon, 27 Jan 2025 19:37:06 +0100
Subject: [PATCH] Variable: add #reject, #rejected? and raise in #wait

---
 lib/async/variable.rb  | 20 ++++++++++++++++++--
 test/async/variable.rb | 24 ++++++++++++++++++++++++
 2 files changed, 42 insertions(+), 2 deletions(-)

diff --git a/lib/async/variable.rb b/lib/async/variable.rb
index 9dffc550..f9efa967 100644
--- a/lib/async/variable.rb
+++ b/lib/async/variable.rb
@@ -30,24 +30,40 @@ def resolve(value = true)
 			
 			condition.signal(value)
 		end
+
+		def reject(error)
+			@error = error
+			condition = @condition
+			@condition = nil
+			
+			self.freeze
+			
+			condition.signal # signal without value
+		end
 		
 		# Alias for {#resolve}.
 		def value=(value)
 			self.resolve(value)
 		end
-		
+
 		# Whether the value has been resolved.
 		#
 		# @returns [Boolean] Whether the value has been resolved.
 		def resolved?
-			@condition.nil?
+			@condition.nil? && @error.nil?
+		end
+
+		def rejected?
+			@condition.nil? && !!@error
 		end
 		
 		# Wait for the value to be resolved.
 		#
 		# @returns [Object] The resolved value.
+		# @raises [Exception] The error with which this Variable was rejected
 		def wait
 			@condition&.wait
+			raise @error if @error
 			return @value
 		end
 		
diff --git a/test/async/variable.rb b/test/async/variable.rb
index b8cdfd9a..479f951b 100644
--- a/test/async/variable.rb
+++ b/test/async/variable.rb
@@ -21,6 +21,14 @@
 		
 		variable.resolve(value)
 	end
+
+	it "can wait for the value to be resolved using setter" do
+		Async do
+			expect(variable.wait).to be == value
+		end
+		
+		variable.value = value
+	end
 	
 	it "can't resolve it a 2nd time" do
 		variable.resolve(value)
@@ -28,6 +36,22 @@
 			variable.resolve(value)
 		end.to raise_exception(FrozenError)
 	end
+
+	it "can reject with an exception" do
+		variable.reject RuntimeError.new("boom")
+		expect(variable).not.to be(:resolved?)
+		expect(variable).to be(:rejected?)
+	end
+
+	it "can wait for a rejection with an error" do
+		Async do
+			expect do
+				variable.wait
+			end.to raise_exception(RuntimeError)
+		end
+		
+		variable.reject(RuntimeError.new)
+	end
 end
 
 include Sus::Fixtures::Async::ReactorContext