GODRIVER-1740 Add check for nil TopologyVersion in Server.Equal() (#519)

Divjot Arora · web-flow · commit 15ac5cfaeca3 · 2020-10-15T14:12:47.000-04:00
diff --git a/mongo/description/server.go b/mongo/description/server.go
@@ -423,11 +423,13 @@ func (s Server) Equal(other Server) bool {
 		return false
 	}
 
-	if s.TopologyVersion.CompareToIncoming(other.TopologyVersion) != 0 {
-		return false
+	// If TopologyVersion is nil for both servers, CompareToIncoming will return -1 because it assumes that the
+	// incoming response is newer. We want the descriptions to be considered equal in this case, though, so an
+	// explicit check is required.
+	if s.TopologyVersion == nil && other.TopologyVersion == nil {
+		return true
 	}
-
-	return true
+	return s.TopologyVersion.CompareToIncoming(other.TopologyVersion) == 0
 }
 
 func sliceStringEqual(a []string, b []string) bool {

Original file line number	Diff line number	Diff line change
`@@ -423,11 +423,13 @@ func (s Server) Equal(other Server) bool {`
`423`	`423`	`return false`
`424`	`424`	`}`
`425`	`425`
`426`		`- if s.TopologyVersion.CompareToIncoming(other.TopologyVersion) != 0 {`
`427`		`- return false`
	`426`	`+ // If TopologyVersion is nil for both servers, CompareToIncoming will return -1 because it assumes that the`
	`427`	`+ // incoming response is newer. We want the descriptions to be considered equal in this case, though, so an`
	`428`	`+ // explicit check is required.`
	`429`	`+ if s.TopologyVersion == nil && other.TopologyVersion == nil {`
	`430`	`+ return true`
`428`	`431`	`}`
`429`		`-`
`430`		`- return true`
	`432`	`+ return s.TopologyVersion.CompareToIncoming(other.TopologyVersion) == 0`
`431`	`433`	`}`
`432`	`434`
`433`	`435`	`func sliceStringEqual(a []string, b []string) bool {`