chore: pr nits, clean up comments, reset resolver state for connectio…

…n unit tests

clientconn.go

@@ -213,8 +213,6 @@ func NewClient(target string, opts ...DialOption) (conn *ClientConn, err error)
 // e.g. to use dns resolver, a "dns:///" prefix should be applied to the target.
 func DialContext(ctx context.Context, target string, opts ...DialOption) (conn *ClientConn, err error) {
 	// At the end of this method, we kick the channel out of idle, rather than waiting for the first rpc.
-	// The eagerConnect option is used to tell the ClientChannel that DialContext was called to make
-	// this channel, and hence tries to connect immediately.
 	cc, err := newClient(target, "passthrough", opts...)
 	if err != nil {
 		return nil, err

clientconn_parsed_target_test.go

@@ -28,16 +28,23 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	"google.golang.org/grpc/credentials/insecure"
+	"google.golang.org/grpc/internal"
 	"google.golang.org/grpc/internal/testutils"
-
 	"google.golang.org/grpc/resolver"
 )
 
 func generateTarget(scheme string, target string) resolver.Target {
 	return resolver.Target{URL: *testutils.MustParseURL(fmt.Sprintf("%s:///%s", scheme, target))}
 }
 
+// This is here just in case another test calls the SetDefaultScheme method.
+func resetInitialResolverState() {
+	resolver.SetDefaultScheme("passthrough")
+	internal.UserSetDefaultScheme = false
+}
+
 func (s) TestParsedTarget_Success_WithoutCustomDialer(t *testing.T) {
+	resetInitialResolverState()
 	dialScheme := resolver.GetDefaultScheme()
 	newClientScheme := "dns"
 	tests := []struct {
@@ -149,6 +156,7 @@ func (s) TestParsedTarget_Failure_WithoutCustomDialer(t *testing.T) {
 }
 
 func (s) TestParsedTarget_WithCustomDialer(t *testing.T) {
+	resetInitialResolverState()
 	defScheme := resolver.GetDefaultScheme()
 	tests := []struct {
 		target            string

resolver/resolver.go

@@ -64,7 +64,7 @@ func Get(scheme string) Builder {
 }
 
 // SetDefaultScheme sets the default scheme that will be used. The default
-// scheme is "passthrough".
+// scheme is initially set to "passthrough".
 //
 // NOTE: this function must only be called during initialization time (i.e. in
 // an init() function), and is not thread-safe. The scheme set last overrides