chore: add more tests (#2547)

zrpc/resolver/internal/directbuilder_test.go

@@ -1,6 +1,7 @@
 package internal
 
 import (
+	"errors"
 	"fmt"
 	"net/url"
 	"strconv"
@@ -35,10 +36,17 @@ func TestDirectBuilder_Build(t *testing.T) {
 			target := fmt.Sprintf("%s:///%s", DirectScheme, strings.Join(servers, ","))
 			uri, err := url.Parse(target)
 			assert.Nil(t, err)
+			cc.err = errors.New("foo")
 			_, err = b.Build(resolver.Target{
 				URL: *uri,
 			}, cc, resolver.BuildOptions{})
-			assert.Nil(t, err)
+			assert.NotNil(t, err)
+			cc.err = nil
+			_, err = b.Build(resolver.Target{
+				URL: *uri,
+			}, cc, resolver.BuildOptions{})
+			assert.NoError(t, err)
+
 			size := mathx.MinInt(test, subsetSize)
 			assert.Equal(t, size, len(cc.state.Addresses))
 			m := make(map[string]lang.PlaceholderType)

zrpc/resolver/internal/resolver_test.go

@@ -16,11 +16,12 @@ func TestNopResolver(t *testing.T) {
 
 type mockedClientConn struct {
 	state resolver.State
+	err   error
 }
 
 func (m *mockedClientConn) UpdateState(state resolver.State) error {
 	m.state = state
-	return nil
+	return m.err
 }
 
 func (m *mockedClientConn) ReportError(err error) {