fix: return error from instance version (#1069)

proxy/proxy/client.go

@@ -575,7 +575,7 @@ func NewConnSrc(instance string, l net.Listener) <-chan Conn {
 	return ch
 }
 
-// InstanceVersionContext uses client cache to return instance version string.
+// InstanceVersion uses client cache to return instance version string.
 //
 // Deprecated: Use Client.InstanceVersionContext instead.
 func (c *Client) InstanceVersion(instance string) (string, error) {
@@ -586,7 +586,7 @@ func (c *Client) InstanceVersion(instance string) (string, error) {
 func (c *Client) InstanceVersionContext(ctx context.Context, instance string) (string, error) {
 	_, _, version, err := c.cachedCfg(ctx, instance)
 	if err != nil {
-		return "", nil
+		return "", err
 	}
 	return version, nil
 }

proxy/proxy/client_test.go

@@ -569,3 +569,47 @@ func TestConnectingWithInvalidConfig(t *testing.T) {
 		t.Fatalf("wanted ErrUnexpectedFailure, got = %v", err)
 	}
 }
+
+var (
+	errLocal  = errors.New("local failed")
+	errRemote = errors.New("remote failed")
+)
+
+type failingCertSource struct{}
+
+func (cs failingCertSource) Local(instance string) (tls.Certificate, error) {
+	return tls.Certificate{}, errLocal
+}
+
+func (cs failingCertSource) Remote(instance string) (cert *x509.Certificate, addr, name, version string, err error) {
+	return nil, "", "", "", errRemote
+}
+
+func TestInstanceVersionContext(t *testing.T) {
+	testCases := []struct {
+		certSource  CertSource
+		wantErr     error
+		wantVersion string
+	}{
+		{
+			certSource:  newCertSource(&fakeCerts{}, forever),
+			wantErr:     nil,
+			wantVersion: "fake version",
+		},
+		{
+			certSource:  failingCertSource{},
+			wantErr:     errLocal,
+			wantVersion: "",
+		},
+	}
+	for _, tc := range testCases {
+		c := newClient(tc.certSource)
+		v, err := c.InstanceVersionContext(context.Background(), instance)
+		if v != tc.wantVersion {
+			t.Fatalf("want version = %v, got version = %v", tc.wantVersion, v)
+		}
+		if err != tc.wantErr {
+			t.Fatalf("want = %v, got = %v", tc.wantErr, err)
+		}
+	}
+}