Tests: Add coverage for AI Client prompts when AI is unsupported

Adds a test to ensure `WP_AI_Client_Prompt_Builder::generate_result()` returns a `WP_Error` with the `prompt_prevented` code and the AI-disabled message when `wp_supports_ai()` returns false.

Follow-up for #64591.

Props nimeshatxecurify.
Fixes #65422.




git-svn-id: https://develop.svn.wordpress.org/trunk@62556 602fd350-edb4-49c9-b593-d223f7449a82

Author: gziolo

tests/phpunit/tests/ai-client/wpAiClientPromptBuilder.php

@@ -2561,6 +2561,23 @@ public function test_generate_result_returns_wp_error_when_filter_prevents_promp
 		$this->assertSame( 'Prompt execution was prevented by a filter.', $result->get_error_message() );
 	}
 
+	/**
+	 * Tests that generate_result returns WP_Error when AI is not supported.
+	 *
+	 * @ticket 65422
+	 */
+	public function test_generate_result_returns_wp_error_when_ai_not_supported() {
+		add_filter( 'wp_supports_ai', '__return_false' );
+
+		$builder = new WP_AI_Client_Prompt_Builder( AiClient::defaultRegistry(), 'Test prompt' );
+
+		$result = $builder->generate_result();
+
+		$this->assertWPError( $result );
+		$this->assertSame( 'prompt_prevented', $result->get_error_code() );
+		$this->assertSame( 'AI features are not supported in this environment.', $result->get_error_message() );
+	}
+
 	/**
 	 * Tests that prevent prompt filter receives a clone of the builder instance.
 	 *