Adds support for conditional steps (#171)

* add support for conditional forms - #

* add testcases - #

* implement the change with a new addIf method - #

* Update src/FormBuilder.php

* Update FormBuilder.php

---------

Co-authored-by: Jess Archer <jess@jessarcher.com>
Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/FormBuilder.php

@@ -32,6 +32,16 @@ public function add(Closure $step, ?string $name = null, bool $ignoreWhenReverti
         return $this;
     }
 
+    /**
+     * Add a new conditional step.
+     */
+    public function addIf(Closure|bool $condition, Closure $step, ?string $name = null, bool $ignoreWhenReverting = false): self
+    {
+        $this->steps[] = new FormStep($step, $condition, $name, $ignoreWhenReverting);
+
+        return $this;
+    }
+
     /**
      * Run all of the given steps.
      *

tests/Feature/FormTest.php

@@ -6,6 +6,7 @@
 use function Laravel\Prompts\confirm;
 use function Laravel\Prompts\form;
 use function Laravel\Prompts\outro;
+use function Laravel\Prompts\text;
 
 it('can run multiple steps', function () {
     Prompt::fake([
@@ -179,3 +180,50 @@
 
     Prompt::assertOutputDoesntContain('This should not appear!');
 });
+
+it('can revert steps with conditions', function () {
+    Prompt::fake([
+        'L', 'u', 'k', 'e', Key::ENTER, // name
+        Key::DOWN, Key::ENTER, // JS
+        Key::CTRL_U, // revert
+        Key::UP, Key::ENTER, // PHP
+        '8', '.', '3', Key::ENTER, // version
+        Key::ENTER,
+    ]);
+
+    $responses = form()
+        ->text('What is your name?')
+        ->select('What is your language?', ['PHP', 'JS'])
+        ->addIf(fn ($responses) => $responses[1] === 'PHP', fn ($responses) => text("Which version?"))
+        ->confirm('Are you sure?')
+        ->submit();
+
+    expect($responses)->toBe([
+        'Luke',
+        'PHP',
+        '8.3',
+        true,
+    ]);
+});
+
+it('leaves skipped conditional field empty', function () {
+    Prompt::fake([
+        'L', 'u', 'k', 'e', Key::ENTER, // name
+        Key::DOWN, Key::ENTER, // JS
+        Key::ENTER,
+    ]);
+
+    $responses = form()
+        ->text('What is your name?')
+        ->select('What is your language?', ['PHP', 'JS'])
+        ->addIf(fn ($responses) => $responses[1] === 'PHP', fn ($responses) => text("Which version?"))
+        ->confirm('Are you sure?')
+        ->submit();
+
+    expect($responses)->toBe([
+        'Luke',
+        'JS',
+        null,
+        true,
+    ]);
+});