From 8951af66d48ac25c286e132eeb5b9b078be4ee7b Mon Sep 17 00:00:00 2001
From: Boone Gorges <boonebgorges@git.wordpress.org>
Date: Mon, 4 Dec 2017 20:51:27 +0000
Subject: [PATCH] Fix regression in `get_tag_link()` since 4.9.

See [42364] for description of the problem.

Because `get_category_link()` is now totally taxonomy-agnostic, `get_tag_link()`
can become a simple wrapper.

Props juiiee8487, markjaquith.
See #42771.

git-svn-id: https://develop.svn.wordpress.org/trunk@42366 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/category-template.php   | 12 +-----
 tests/phpunit/tests/term/getTagLink.php | 57 +++++++++++++++++++++++++
 2 files changed, 58 insertions(+), 11 deletions(-)
 create mode 100644 tests/phpunit/tests/term/getTagLink.php

diff --git a/src/wp-includes/category-template.php b/src/wp-includes/category-template.php
index 77c0d4532a..27061e7266 100644
--- a/src/wp-includes/category-template.php
+++ b/src/wp-includes/category-template.php
@@ -1111,17 +1111,7 @@ function walk_category_dropdown_tree() {
  * @return string Link on success, empty string if tag does not exist.
  */
 function get_tag_link( $tag ) {
-	if ( ! is_object( $tag ) ) {
-		$tag = (int) $tag;
-	}
-
-	$tag = get_term_link( $tag, 'post_tag' );
-
-	if ( is_wp_error( $tag ) ) {
-		return '';
-	}
-
-	return $tag;
+	return get_category_link( $tag );
 }
 
 /**
diff --git a/tests/phpunit/tests/term/getTagLink.php b/tests/phpunit/tests/term/getTagLink.php
new file mode 100644
index 0000000000..5b28c1d5dc
--- /dev/null
+++ b/tests/phpunit/tests/term/getTagLink.php
@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * @group taxonomy
+ * @covers ::get_tag_link
+ */
+class Tests_Term_GetTagLink extends WP_UnitTestCase {
+	public function test_success() {
+		$t = self::factory()->term->create( array(
+			'taxonomy' => 'post_tag',
+			'slug' => 'term-slug',
+		) );
+
+		$found = get_tag_link( $t );
+		$expected = home_url( '?tag=term-slug' );
+
+		$this->assertSame( $expected, $found );
+	}
+
+	/**
+	 * @ticket 42771
+	 */
+	public function test_should_return_link_for_term_from_another_taxonomy_on_primed_cache() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$t = self::factory()->term->create( array(
+			'taxonomy' => 'wptests_tax',
+			'slug'     => 'test-term',
+		) );
+
+		$term = get_term( $t );
+
+		$found = get_tag_link( $t );
+		$expected = home_url( '?wptests_tax=test-term' );
+
+		$this->assertSame( $expected, $found );
+	}
+
+	/**
+	 * @ticket 42771
+	 */
+	public function test_should_return_link_for_term_from_another_taxonomy_on_empty_cache() {
+		register_taxonomy( 'wptests_tax', 'post' );
+
+		$t = self::factory()->term->create( array(
+			'taxonomy' => 'wptests_tax',
+			'slug'     => 'test-term',
+		) );
+
+		clean_term_cache( $t );
+
+		$found = get_tag_link( $t );
+		$expected = home_url( '?wptests_tax=test-term' );
+
+		$this->assertSame( $expected, $found );
+	}
+}