Check that the jwt token is valid when running fly targets

[nazrhom]

I don't know go at all, but this seemed like a pretty straightforward change. Let me know if there is anything else to add (e.g. tests) but please keep in mind I might need some guidance.
Thanks.

Fixes: #4107
Change-type: patch
Signed-off-by: Giovanni Garufi giovanni@balena.io

[jamieklassen]

This feels like a very sensible change. While trying to advise you, @jomsie and I kinda wrote an integration test on your behalf - if you're feeling ambitious you could try to break this logic down into finer-grained unit tests, but they do seem to be lacking in the fly codebase. So take this example and do with it as you wish, but let's have some kind of test!

diff --git a/fly/integration/fixtures/flyrc-badtoken.yml b/fly/integration/fixtures/flyrc-badtoken.yml
new file mode 100644
index 000000000..4238f7770
--- /dev/null
+++ b/fly/integration/fixtures/flyrc-badtoken.yml
@@ -0,0 +1,7 @@
+targets:
+  test:
+    api: https://example.com/test
+    team: test
+    token:
+      type: Bearer
+      value: banana
diff --git a/fly/integration/targets_test.go b/fly/integration/targets_test.go
index 49a9b457b..70f5960d5 100644
--- a/fly/integration/targets_test.go
+++ b/fly/integration/targets_test.go
@@ -9,6 +9,7 @@ import (
 	"github.com/concourse/concourse/fly/ui"
 	"github.com/fatih/color"
 	"github.com/onsi/gomega/gexec"
+	"github.com/onsi/gomega/gbytes"
 
 	. "github.com/onsi/ginkgo"
 	. "github.com/onsi/gomega"
@@ -16,12 +17,13 @@ import (
 
 var _ = Describe("Fly CLI", func() {
 	var (
-		flyCmd *exec.Cmd
-		flyrc  string
-		tmpDir string
+		flyCmd       *exec.Cmd
+		flyrc        string
+		tmpDir       string
+		flyrcFixture string
 	)
 
-	BeforeEach(func() {
+	JustBeforeEach(func() {
 		var err error
 		tmpDir, err = ioutil.TempDir("", "fly-test")
 		Expect(err).NotTo(HaveOccurred())
@@ -29,7 +31,7 @@ var _ = Describe("Fly CLI", func() {
 		os.Setenv("HOME", tmpDir)
 		flyrc = filepath.Join(userHomeDir(), ".flyrc")
 
-		flyFixtureFile, err := os.OpenFile("./fixtures/flyrc.yml", os.O_RDONLY, 0600)
+		flyFixtureFile, err := os.OpenFile(flyrcFixture, os.O_RDONLY, 0600)
 		Expect(err).NotTo(HaveOccurred())
 
 		flyFixtureData, err := ioutil.ReadAll(flyFixtureFile)
@@ -41,6 +43,10 @@ var _ = Describe("Fly CLI", func() {
 		flyCmd = exec.Command(flyPath, "targets")
 	})
 
+	BeforeEach(func() {
+		flyrcFixture = "./fixtures/flyrc.yml"
+	})
+
 	AfterEach(func() {
 		os.RemoveAll(tmpDir)
 	})
@@ -70,6 +76,21 @@ var _ = Describe("Fly CLI", func() {
 			})
 		})
 
+		Context("when the .flyrc contains a target with an invalid token", func() {
+			BeforeEach(func() {
+				flyrcFixture = "./fixtures/flyrc-badtoken.yml"
+			})
+
+			It("shows an error message", func() {
+				sess, err := gexec.Start(flyCmd, GinkgoWriter, GinkgoWriter)
+				Expect(err).NotTo(HaveOccurred())
+
+				Eventually(sess).Should(gexec.Exit(1))
+
+				Expect(sess.Err).To(gbytes.Say("token validation failed"))
+			})
+		})
+
 		Context("when no targets are available", func() {
 			BeforeEach(func() {
 				os.RemoveAll(flyrc)