Add workflow id conflict policy to signal with start

src/Temporalio/Client/TemporalClient.Workflow.cs

@@ -607,6 +607,7 @@ private async Task<WorkflowHandle<TWorkflow, TResult>> StartWorkflowInternalAsyn
                     Header = req.Header,
                     WorkflowStartDelay = req.WorkflowStartDelay,
                     SignalName = input.Options.StartSignal,
+                    WorkflowIdConflictPolicy = input.Options.IdConflictPolicy,
                 };
                 if (input.Options.StartSignalArgs != null && input.Options.StartSignalArgs.Count > 0)
                 {

tests/Temporalio.Tests/Worker/WorkflowWorkerTests.cs

@@ -5618,9 +5618,20 @@ await AssertWarnings(
     [Workflow]
     public class IdConflictWorkflow
     {
+        private string signal = "nothing";
+
         // Just wait forever
         [WorkflowRun]
         public Task RunAsync() => Workflow.WaitConditionAsync(() => false);
+
+        [WorkflowSignal]
+        public async Task TheSignal(string sig)
+        {
+            signal = sig;
+        }
+
+        [WorkflowQuery]
+        public string GetSignal() => signal;
     }
 
     [Fact]
@@ -5648,6 +5659,7 @@ await Assert.ThrowsAsync<WorkflowAlreadyStartedException>(() =>
                     {
                         IdConflictPolicy = WorkflowIdConflictPolicy.Fail,
                     }));
+            // signal-with-start does not allow fail policy
 
             // Confirm gives back same handle if requested
             var newHandle = await Env.Client.StartWorkflowAsync(
@@ -5660,6 +5672,19 @@ await Assert.ThrowsAsync<WorkflowAlreadyStartedException>(() =>
             Assert.Equal(handle.RunId, newHandle.RunId);
             Assert.Equal(WorkflowExecutionStatus.Running, (await handle.DescribeAsync()).Status);
             Assert.Equal(WorkflowExecutionStatus.Running, (await newHandle.DescribeAsync()).Status);
+            // Also with signal-with-start
+            newHandle = await Env.Client.StartWorkflowAsync(
+                (IdConflictWorkflow wf) => wf.RunAsync(),
+                new(id: handle.Id, taskQueue: worker.Options.TaskQueue!)
+                {
+                    StartSignal = "TheSignal",
+                    StartSignalArgs = new[] { "hi!" },
+                    IdConflictPolicy = WorkflowIdConflictPolicy.UseExisting,
+                });
+            newHandle = newHandle with { RunId = newHandle.ResultRunId };
+            Assert.Equal(handle.RunId, newHandle.RunId);
+            Assert.Equal(WorkflowExecutionStatus.Running, (await handle.DescribeAsync()).Status);
+            Assert.Equal(WorkflowExecutionStatus.Running, (await newHandle.DescribeAsync()).Status);
 
             // Confirm terminates and starts new if requested
             newHandle = await Env.Client.StartWorkflowAsync(
@@ -5672,6 +5697,22 @@ await Assert.ThrowsAsync<WorkflowAlreadyStartedException>(() =>
             Assert.NotEqual(handle.RunId, newHandle.RunId);
             Assert.Equal(WorkflowExecutionStatus.Terminated, (await handle.DescribeAsync()).Status);
             Assert.Equal(WorkflowExecutionStatus.Running, (await newHandle.DescribeAsync()).Status);
+            // Also with signal-with-start
+            newHandle = await Env.Client.StartWorkflowAsync(
+                (IdConflictWorkflow wf) => wf.RunAsync(),
+                new(id: handle.Id, taskQueue: worker.Options.TaskQueue!)
+                {
+                    StartSignal = "TheSignal",
+                    StartSignalArgs = new[] { "hi!" },
+                    IdConflictPolicy = WorkflowIdConflictPolicy.TerminateExisting,
+                });
+            newHandle = newHandle with { RunId = newHandle.ResultRunId };
+            Assert.NotEqual(handle.RunId, newHandle.RunId);
+            Assert.Equal(WorkflowExecutionStatus.Terminated, (await handle.DescribeAsync()).Status);
+            Assert.Equal(WorkflowExecutionStatus.Running, (await newHandle.DescribeAsync()).Status);
+            // Ensure it actually got the signal this time
+            var queryRes = await newHandle.QueryAsync(wf => wf.GetSignal());
+            Assert.Equal("hi!", queryRes);
         });
     }