Fix the issue with message dispatcher and channels

Resolved a previous error where each subscription would create a new
channel with the fixed buffer size. This caused blocking when the
channel buffer was full, preventing the client from handling additional messages.

Now, there is a `subscriptions` struct that holds a queue for receiving
notifications, ensuring the notify function does not block.

1 files changed, 86 insertions, 0 deletions

diff --git a/jsonrpc/client/subscription_test.go b/jsonrpc/client/subscription_test.go
new file mode 100644
index 0000000..5928665
--- /dev/null
+++ b/jsonrpc/client/subscription_test.go
@@ -0,0 +1,86 @@
+package client
+
+import (
+	"encoding/json"
+	"sync"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSubscriptionFullQueue(t *testing.T) {
+	bufSize := 100
+	sub := newSubscription(1, bufSize)
+
+	var wg sync.WaitGroup
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer sub.stop()
+		for i := 0; i < bufSize+10; i++ {
+			b, err := json.Marshal(i)
+			assert.Nil(t, err)
+			err = sub.notify(b)
+			if i > bufSize {
+				if assert.Error(t, err) {
+					assert.ErrorIs(t, err, queueIsFullErr)
+				}
+			}
+		}
+	}()
+
+	wg.Wait()
+}
+
+func TestSubscriptionRecv(t *testing.T) {
+	bufSize := 100
+	sub := newSubscription(1, bufSize)
+
+	var wg sync.WaitGroup
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for i := 0; i < bufSize; i++ {
+			b, err := json.Marshal(i)
+			assert.Nil(t, err)
+			err = sub.notify(b)
+			assert.Nil(t, err)
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		i := 0
+		for nt := range sub.Recv() {
+			var v int
+			err := json.Unmarshal(nt, &v)
+			assert.Nil(t, err)
+			assert.Equal(t, v, i)
+			i += 1
+			if i == bufSize {
+				break
+			}
+		}
+	}()
+
+	wg.Wait()
+}
+
+func TestSubscriptionStop(t *testing.T) {
+	sub := newSubscription(1, 10)
+
+	sub.stop()
+
+	_, ok := <-sub.Recv()
+	assert.False(t, ok)
+
+	b, err := json.Marshal(1)
+	assert.Nil(t, err)
+	err = sub.notify(b)
+	if assert.Error(t, err) {
+		assert.ErrorIs(t, err, subscriptionIsClosedErr)
+	}
+}