gitlab: simplify terminal/interaction checks

Simplify where we check for user interaction and/or terminal prompts
during authentication, to only need to check at the start of each
`GetAuthenticationAsync` call.

Note that is is a behaviour change - we now require user interaction to
be allowed to perform authentication even with only 1 mode available.
This is technically more 'correct' because when the user disables
interactivity, we should never require interaction to continue. Although
we are not asking the user to select a mode of authentication, we still
either need them to enter a username/password, or respond to a browser
OAuth flow.

Author: mjcheetham

src/shared/GitLab.Tests/GitLabAuthenticationTests.cs

@@ -20,11 +20,10 @@ await Assert.ThrowsAsync<ArgumentException>("modes",
 
         [Theory]
         [InlineData(AuthenticationModes.Browser)]
-        public async Task GitLabAuthentication_GetAuthenticationAsync_SingleChoice_TerminalAndInteractionNotRequired(GitLab.AuthenticationModes modes)
+        public async Task GitLabAuthentication_GetAuthenticationAsync_SingleChoice_InteractionStillRequired(GitLab.AuthenticationModes modes)
         {
             var context = new TestCommandContext();
-            context.Settings.IsTerminalPromptsEnabled = false;
-            context.Settings.IsInteractionAllowed = false;
+            context.Settings.IsInteractionAllowed = true;
             context.SessionManager.IsDesktopSession = true; // necessary for browser
             context.Settings.IsGuiPromptsEnabled = false;
             var auth = new GitLabAuthentication(context);

src/shared/GitLab/GitLabAuthentication.cs

@@ -70,6 +70,8 @@ public async Task<AuthenticationPromptResult> GetAuthenticationAsync(Uri targetU
                 throw new ArgumentException(@$"Must specify at least one {nameof(AuthenticationModes)}", nameof(modes));
             }
 
+            ThrowIfUserInteractionDisabled();
+
             if (Context.Settings.IsGuiPromptsEnabled && Context.SessionManager.IsDesktopSession)
             {
                 if (TryFindHelperCommand(out string helperCommand, out string args))
@@ -132,11 +134,11 @@ private async Task<AuthenticationPromptResult> GetAuthenticationViaUiAsync(
 
         private AuthenticationPromptResult GetAuthenticationViaTty(Uri targetUri, string userName, AuthenticationModes modes)
         {
+            ThrowIfTerminalPromptsDisabled();
+
             switch (modes)
             {
                 case AuthenticationModes.Basic:
-                    ThrowIfUserInteractionDisabled();
-                    ThrowIfTerminalPromptsDisabled();
                     Context.Terminal.WriteLine("Enter GitLab credentials for '{0}'...", targetUri);
 
                     if (string.IsNullOrWhiteSpace(userName))
@@ -152,8 +154,6 @@ private AuthenticationPromptResult GetAuthenticationViaTty(Uri targetUri, string
                     return new AuthenticationPromptResult(AuthenticationModes.Basic, new GitCredential(userName, password));
 
                 case AuthenticationModes.Pat:
-                    ThrowIfUserInteractionDisabled();
-                    ThrowIfTerminalPromptsDisabled();
                     Context.Terminal.WriteLine("Enter GitLab credentials for '{0}'...", targetUri);
 
                     if (string.IsNullOrWhiteSpace(userName))
@@ -176,8 +176,6 @@ private AuthenticationPromptResult GetAuthenticationViaTty(Uri targetUri, string
                         @$"At least one {nameof(AuthenticationModes)} must be supplied");
 
                 default:
-                    ThrowIfUserInteractionDisabled();
-                    ThrowIfTerminalPromptsDisabled();
                     var menuTitle = $"Select an authentication method for '{targetUri}'";
                     var menu = new TerminalMenu(Context.Terminal, menuTitle);