GODRIVER-908 Fix err merging on options.ClientOptions

Author: Mathieu

mongo/client.go

@@ -76,11 +76,6 @@ func Connect(ctx context.Context, opts ...*options.ClientOptions) (*Client, erro
 func NewClient(opts ...*options.ClientOptions) (*Client, error) {
 	clientOpt := options.MergeClientOptions(opts...)
 
-	err := clientOpt.Validate()
-	if err != nil {
-		return nil, err
-	}
-
 	id, err := uuid.New()
 	if err != nil {
 		return nil, err

mongo/options/clientoptions.go

@@ -505,6 +505,9 @@ func MergeClientOptions(opts ...*ClientOptions) *ClientOptions {
 		if opt.ZlibLevel != nil {
 			c.ZlibLevel = opt.ZlibLevel
 		}
+		if opt.err != nil {
+			c.err = opt.err
+		}
 	}
 
 	return c

mongo/options/clientoptions_test.go

@@ -151,6 +151,18 @@ func TestClientOptions(t *testing.T) {
 				t.Errorf("Merged client options do not match. got %v; want %v", got, want)
 			}
 		})
+
+		// go-cmp dont support error comparisons (https://github.com/google/go-cmp/issues/24)
+		// Use specifique test for this
+		t.Run("MergeClientOptions/err", func(t *testing.T) {
+			opt1, opt2 := Client(), Client()
+			opt1.err = errors.New("Test error")
+
+			got := MergeClientOptions(nil, opt1, opt2)
+			if got.err.Error() != "Test error" {
+				t.Errorf("Merged client options do not match. got %v; want %v", got.err.Error(), opt1.err.Error())
+			}
+		})
 	})
 	t.Run("ApplyURI", func(t *testing.T) {
 		baseClient := func() *ClientOptions {