chore: add get expiry method for sts auth

auth/sts.go

@@ -83,6 +83,15 @@ func (a *STSAuth) GetToken(*os.File) (string, error) {
 	return a.token, err
 }
 
+// GetExpiry returns the expiry time of the token if it already exists. Otherwise,
+// it returns a zero-valued time.Time struct and an error.
+func (a *STSAuth) GetExpiry(*os.File) (time.Time, error) {
+	if len(a.token) > 0 {
+		return a.expiry, nil
+	}
+	return time.Time{}, fmt.Errorf("Expiry time not set.")
+}
+
 func (a *STSAuth) authenticate() error {
 	builtURL := *a.baseURL
 	builtURL.Path = "v2/auth/sts-identity"

auth/sts_test.go

@@ -171,6 +171,31 @@ func TestGetTokenSTS(t *testing.T) {
 		}))
 }
 
+func TestGetExpiry(t *testing.T) {
+	Convey("A valid STSAuth", t, func() {
+		a, err := NewSTSAuth("https://test.example.com", "us-west-2")
+		So(err, ShouldBeNil)
+		So(a, ShouldNotBeNil)
+		a.expiry = time.Now()
+		a.token = "token"
+		Convey("Should return an expiry time", func() {
+			exp, err := a.GetExpiry(nil)
+			So(exp, ShouldNotBeNil)
+			So(err, ShouldBeNil)
+		})
+	})
+	Convey("An unauthenticated STSAuth", t, func() {
+		a, err := NewSTSAuth("https://test.example.com", "us-west-2")
+		So(err, ShouldBeNil)
+		So(a, ShouldNotBeNil)
+		Convey("Should return an error", func() {
+			exp, err := a.GetExpiry(nil)
+			So(exp, ShouldBeZeroValue)
+			So(err, ShouldNotBeNil)
+		})
+	})
+}
+
 func TestIsAuthenticated(t *testing.T) {
 	Convey("A valid STSAuth", t, func() {
 		a, err := NewSTSAuth("https://test.example.com", "us-west-2")