Cancel Handler context when connection closes

conn_test.go

@@ -14,6 +14,40 @@ import (
 	"github.com/sourcegraph/jsonrpc2"
 )
 
+func TestConn(t *testing.T) {
+	t.Run("cancels context when closed", func(t *testing.T) {
+		ctxCanceled := make(chan struct{})
+
+		handler := handlerFunc(func(ctx context.Context, c *jsonrpc2.Conn, r *jsonrpc2.Request) {
+			// Block until the context is canceled.
+			<-ctx.Done()
+			close(ctxCanceled)
+		})
+
+		connA, connB := Pipe(noopHandler{}, jsonrpc2.AsyncHandler(handler))
+		defer connA.Close()
+		defer connB.Close()
+
+		// Send a notification from connA to connB to trigger connB's handler
+		// function.
+		if err := connA.Notify(context.Background(), "foo", nil, nil); err != nil {
+			t.Fatal(err)
+		}
+
+		// Disconnect connA from connB.
+		if err := connA.Close(); err != nil {
+			t.Fatal(err)
+		}
+
+		select {
+		case <-ctxCanceled:
+			// Test passed, the handler's context was canceled.
+		case <-time.After(time.Second):
+			t.Fatal("context not canceled")
+		}
+	})
+}
+
 var paramsTests = []struct {
 	sendParams interface{}
 	wantParams *json.RawMessage
@@ -198,12 +232,12 @@ func testParams(t *testing.T, want *json.RawMessage, fn func(c *jsonrpc2.Conn) e
 		wg.Done()
 	})
 
-	client, server := newClientServer(handler)
-	defer client.Close()
-	defer server.Close()
+	connA, connB := Pipe(noopHandler{}, handler)
+	defer connA.Close()
+	defer connB.Close()
 
 	wg.Add(1)
-	if err := fn(client); err != nil {
+	if err := fn(connA); err != nil {
 		t.Error(err)
 	}
 	wg.Wait()
@@ -242,18 +276,12 @@ func assertRawJSONMessage(t *testing.T, got *json.RawMessage, want *json.RawMess
 	}
 }
 
-func newClientServer(handler jsonrpc2.Handler) (client *jsonrpc2.Conn, server *jsonrpc2.Conn) {
+// Pipe returns two jsonrpc2.Conn, connected via a synchronous, in-memory, full
+// duplex network connection.
+func Pipe(handlerA, handlerB jsonrpc2.Handler) (connA *jsonrpc2.Conn, connB *jsonrpc2.Conn) {
 	ctx := context.Background()
-	connA, connB := net.Pipe()
-	client = jsonrpc2.NewConn(
-		ctx,
-		jsonrpc2.NewPlainObjectStream(connA),
-		noopHandler{},
-	)
-	server = jsonrpc2.NewConn(
-		ctx,
-		jsonrpc2.NewPlainObjectStream(connB),
-		handler,
-	)
-	return client, server
+	a, b := net.Pipe()
+	connA = jsonrpc2.NewConn(ctx, jsonrpc2.NewPlainObjectStream(a), handlerA)
+	connB = jsonrpc2.NewConn(ctx, jsonrpc2.NewPlainObjectStream(b), handlerB)
+	return connA, connB
 }