update post 'create/update'

update code according to review and modify tests

Author: thrijith

features/post.feature

@@ -47,23 +47,13 @@ Feature: Manage WordPress posts
     When I try `wp post update {POST_ID} --post_category=test`
     Then STDERR should be:
       """
-      Warning: Unable to set test as post category
-      """
-    And STDOUT should be:
-      """
-      Success: Updated post {POST_ID}.
+      Error: No such post category 'test'.
       """
 
     When I try `wp post create --post_title="Test category two" --post_category={SECOND_TERM_ID},Test --porcelain`
-    Then STDOUT should be a number
-    And save STDOUT as {POST_ID_TWO}
     Then STDERR should be:
       """
-      Warning: Unable to set Test as post category
-      """
-    And STDOUT should be:
-      """
-      {POST_ID_TWO}
+      Error: No such post category 'Test'.
       """
 
   Scenario: Creating/getting/editing posts

src/Post_Command.php

@@ -760,13 +760,14 @@ private function get_category_ids( $arg ) {
 
 		foreach ( $categoires as $post_category ) {
 			if ( trim( $post_category ) !== '' ) {
-				$post_category = ( true === is_numeric( $post_category ) ) ? intval( $post_category ) : $post_category;
-
-				$category_id = category_exists( $post_category );
-
-				if ( null === $category_id ) {
+				if ( is_numeric( $post_category ) && (int) $post_category ) {
+					$category_id = category_exists( (int) $post_category );
+				} else {
+					$category_id = category_exists( $post_category );
+				}
+				if ( ! $category_id ) {
 					$category_ids[] = $post_category;
-					WP_CLI::warning( "Unable to set $post_category as post category" );
+					WP_CLI::error( "No such post category '$post_category'." );
 				} else {
 					$category_ids[] = $category_id;
 				}