HTTP mocking: support filename option (#332)

Author: swissspidy

features/http-mocking.feature

@@ -119,3 +119,20 @@ Feature: HTTP request mocking
     Then STDOUT should be a table containing rows:
       | version | update_type | package_url |
       | 999.9.9 | major       | https://downloads.wordpress.org/release/wordpress-999.9.9.zip |
+
+  Scenario: Mock HTTP request with filename option writes to disk
+    Given an empty directory
+    And that HTTP requests to https://example.com/mocked-file.txt will respond with:
+      """
+      HTTP/1.1 200 OK
+      Content-Type: text/plain
+
+      Mocked file contents on disk!
+      """
+
+    When I try `wp eval 'WP_CLI\Utils\http_request("GET", "https://example.com/mocked-file.txt", null, [], ["filename" => "downloaded.txt"]);' --skip-wordpress`
+    Then the return code should be 0
+    And the downloaded.txt file should contain:
+      """
+      Mocked file contents on disk!
+      """

src/Context/GivenStepDefinitions.php

@@ -228,6 +228,14 @@ public function request( \$url, \$headers = array(), \$data = array(), \$options
 				if ( false !== \$pos ) {
 					\$response = substr( \$response, 0, \$pos ) . "\\r\\n\\r\\n" . substr( \$response, \$pos + 2 );
 				}
+				if ( ! empty( \$options['filename'] ) ) {
+					\$body = '';
+					\$body_pos = strpos( \$response, "\\r\\n\\r\\n" );
+					if ( false !== \$body_pos ) {
+						\$body = substr( \$response, \$body_pos + 4 );
+					}
+					file_put_contents( \$options['filename'], \$body );
+				}
 				return \$response;
 			}
 		}
@@ -313,6 +321,10 @@ static function( \$pre, \$parsed_args, \$url ) {
 					);
 				}
 
+				if ( ! empty( \$parsed_args['filename'] ) ) {
+					file_put_contents( \$parsed_args['filename'], \$response->body );
+				}
+
 				return array(
 					'headers'  => \$response->headers->getAll(),
 					'body'     => \$response->body,