Prevent RunTestConcurrency from creating garbage clients (#793)

Change `RunTestTreeConcurrency` in `tree_concurrency_test.go` not
to create and close clients in each test. This commit can solve the
performance degradation problem that occurs when vector clocks are
used.

test/integration/tree_concurrency_test.go

@@ -207,16 +207,17 @@ func (op editOperationType) run(t *testing.T, doc *document.Document, user int,
 func RunTestTreeConcurrency(testDesc string, t *testing.T, initialState json.TreeNode, initialXML string,
 	rangesArr []twoRangesType, opArr1, opArr2 []operationInterface) {
 
+	clients := activeClients(t, 2)
+	c1, c2 := clients[0], clients[1]
+	defer deactivateAndCloseClients(t, clients)
+
+	ctx := context.Background()
+	d1 := document.New(helper.TestDocKey(t))
+	assert.NoError(t, c1.Attach(ctx, d1))
+	d2 := document.New(helper.TestDocKey(t))
+	assert.NoError(t, c2.Attach(ctx, d2))
+
 	runTest := func(ranges twoRangesType, op1, op2 operationInterface) testResult {
-		clients := activeClients(t, 2)
-		c1, c2 := clients[0], clients[1]
-		defer deactivateAndCloseClients(t, clients)
-
-		ctx := context.Background()
-		d1 := document.New(helper.TestDocKey(t))
-		assert.NoError(t, c1.Attach(ctx, d1))
-		d2 := document.New(helper.TestDocKey(t))
-		assert.NoError(t, c2.Attach(ctx, d2))
 
 		assert.NoError(t, d1.Update(func(root *json.Object, p *presence.Presence) error {
 			root.SetNewTree("t", &initialState)

test/integration/tree_test.go

@@ -425,7 +425,7 @@ func TestTree(t *testing.T) {
 			root.GetTree("t").EditBulk(3, 3, []*json.TreeNode{{
 				Type:  "text",
 				Value: "c",
-			}, &json.TreeNode{
+			}, {
 				Type:  "text",
 				Value: "d",
 			}}, 0)
@@ -451,7 +451,7 @@ func TestTree(t *testing.T) {
 			root.GetTree("t").EditBulk(4, 4, []*json.TreeNode{{
 				Type:     "p",
 				Children: []json.TreeNode{{Type: "text", Value: "cd"}},
-			}, &json.TreeNode{
+			}, {
 				Type:     "i",
 				Children: []json.TreeNode{{Type: "text", Value: "fg"}},
 			}}, 0)