Validate PR passed as pr view <url> before opening it

command/pr.go

@@ -260,7 +260,8 @@ func prFromArg(apiClient *api.Client, baseRepo context.GitHubRepository, arg str
 	}
 
 	if m := prURLRE.FindStringSubmatch(arg); m != nil {
-		return &api.PullRequest{URL: m[0]}, nil
+		prNumber, _ := strconv.Atoi(m[3])
+		return api.PullRequestByNumber(apiClient, baseRepo, prNumber)
 	}
 
 	return api.PullRequestForBranch(apiClient, baseRepo, arg)
@@ -332,15 +333,6 @@ func prCheckout(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return err
 	}
-	if pr.Number == 0 {
-		// hydrate the pr object by fetching extra information from the API
-		m := prURLRE.FindStringSubmatch(pr.URL)
-		prNumber, _ := strconv.Atoi(m[3])
-		pr, err = api.PullRequestByNumber(apiClient, baseRemote, prNumber)
-		if err != nil {
-			return err
-		}
-	}
 
 	headRemote := baseRemote
 	if pr.IsCrossRepository {

command/pr_test.go

@@ -256,7 +256,13 @@ func TestPRView_numberArg(t *testing.T) {
 
 func TestPRView_urlArg(t *testing.T) {
 	initBlankContext("OWNER/REPO", "master")
-	initFakeHTTP()
+	http := initFakeHTTP()
+
+	http.StubResponse(200, bytes.NewBufferString(`
+	{ "data": { "repository": { "pullRequest": {
+		"url": "https://github.com/OWNER/REPO/pull/23"
+	} } } }
+	`))
 
 	var seenCmd *exec.Cmd
 	restoreCmd := utils.SetPrepareCmd(func(cmd *exec.Cmd) utils.Runnable {