approve/unapprove: Provide better error messages for repeat actions

Users are presented with the following error message if an already
approved MR is approved again:

2021/05/07 10:34:35 mr_approve.go:55: POST https://gitlab.com/api/v4/projects/24140364/merge_requests/119/approve: 401 {message: 401 Unauthorized}

Similarily, when an unapproved MR is unapproved again:

2021/05/07 10:35:01 mr_unapprove.go:55: POST https://gitlab.com/api/v4/projects/24140364/merge_requests/119/unapprove: 40

These messages are confusing and should state that the MR was already
approved or unapproved.

Add better error messages for repeat approve and unapprove actions.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>

cmd/ci_run_test.go

@@ -123,7 +123,7 @@ func Test_getCIRunOptions(t *testing.T) {
 			[]string{},
 			nil, // https://gitlab.com/zaquestion/test project ID
 			"",
-			"gitlab project not found, verify you have access to the requested resource",
+			"GitLab project not found, verify you have access to the requested resource",
 		},
 	}
 

cmd/mr_approve.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"fmt"
 	"log"
+	"os"
 
 	"github.com/rsteube/carapace"
 	"github.com/spf13/cobra"
@@ -52,7 +53,13 @@ var mrApproveCmd = &cobra.Command{
 
 		err = lab.MRApprove(p.ID, int(id))
 		if err != nil {
-			log.Fatal(err)
+			if err == lab.ErrStatusForbidden {
+				log.Fatal(err)
+			}
+			if err == lab.ErrActionRepeated {
+				fmt.Printf("Merge Request !%d already approved\n", id)
+				os.Exit(1)
+			}
 		}
 		fmt.Printf("Merge Request !%d approved\n", id)
 	},

cmd/mr_unapprove.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"fmt"
 	"log"
+	"os"
 
 	"github.com/rsteube/carapace"
 	"github.com/spf13/cobra"
@@ -52,7 +53,13 @@ var mrUnapproveCmd = &cobra.Command{
 
 		err = lab.MRUnapprove(p.ID, int(id))
 		if err != nil {
-			log.Fatal(err)
+			if err == lab.ErrStatusForbidden {
+				log.Fatal(err)
+			}
+			if err == lab.ErrActionRepeated {
+				fmt.Printf("Merge Request !%d already unapproved\n", id)
+				os.Exit(1)
+			}
 		}
 		fmt.Printf("Merge Request !%d unapproved\n", id)
 	},

internal/gitlab/gitlab.go

@@ -26,6 +26,9 @@ import (
 )
 
 var (
+	// ErrActionRepeated is returned when a GitLab action is executed again.  For example
+	// this can be returned when an MR is approved twice.
+	ErrActionRepeated = errors.New("GitLab action repeated")
 	// ErrGroupNotFound is returned when a GitLab group cannot be found.
 	ErrGroupNotFound = errors.New("GitLab group not found")
 	// ErrNotModified is returned when adding an already existing item to a Todo list
@@ -526,6 +529,10 @@ func MRApprove(pid interface{}, id int) error {
 	if resp != nil && resp.StatusCode == http.StatusForbidden {
 		return ErrStatusForbidden
 	}
+	if resp != nil && resp.StatusCode == http.StatusUnauthorized {
+		// returns 401 if the MR has already been approved
+		return ErrActionRepeated
+	}
 	if err != nil {
 		return err
 	}
@@ -538,6 +545,10 @@ func MRUnapprove(pid interface{}, id int) error {
 	if resp != nil && resp.StatusCode == http.StatusForbidden {
 		return ErrStatusForbidden
 	}
+	if resp != nil && resp.StatusCode == http.StatusNotFound {
+		// returns 404 if the MR has already been unapproved
+		return ErrActionRepeated
+	}
 	if err != nil {
 		return err
 	}