update post 'create/update'

fix tests

Author: thrijith

features/post.feature

@@ -44,13 +44,28 @@ Feature: Manage WordPress posts
       Success: Updated post {POST_ID}.
       """
 
-    When I run `wp post update {POST_ID} --post_category=test --porcelain`
-    Then STDOUT should be:
+    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}.
       """
 
+    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}
+      """
+
   Scenario: Creating/getting/editing posts
     Given a content.html file:
       """

src/Post_Command.php

@@ -759,14 +759,17 @@ private function get_category_ids( $arg ) {
 		$categoires = explode( ',', $arg );
 
 		foreach ( $categoires as $post_category ) {
-			$post_category = ( true === is_numeric( $post_category ) ) ? intval( $post_category ) : $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 ) {
-				$category_ids[] = $post_category;
-				WP_CLI::warning( "Unable to set $post_category as post category" );
-			} else {
-				$category_ids[] = $category_id;
+				$category_id = category_exists( $post_category );
+
+				if ( null === $category_id ) {
+					$category_ids[] = $post_category;
+					WP_CLI::warning( "Unable to set $post_category as post category" );
+				} else {
+					$category_ids[] = $category_id;
+				}
 			}
 		}
 		return $category_ids;