Taxonomy: Test inserting a child term flushes queries by term ID.

Adds a test to ensure that interting a child term invalidates the cache of a `get_terms()` query by the parent ID.

Props Dekadinious, peterwilsoncc.
See #62031, #61530.



git-svn-id: https://develop.svn.wordpress.org/trunk@59015 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/term/cache.php

@@ -445,4 +445,56 @@ public function test_get_object_term_cache_should_return_error_if_any_term_is_an
 		$terms = get_the_terms( $p, 'wptests_tax' );
 		$this->assertWPError( $terms );
 	}
+
+	/**
+	 * Ensures that the term query cache is cleared when a child term is inserted.
+	 *
+	 * @ticket 62031
+	 */
+	public function test_inserting_child_term_clears_the_query_cache() {
+		register_taxonomy(
+			'wptests_tax',
+			'post',
+			array(
+				'hierarchical' => true,
+			)
+		);
+
+		$parent = self::factory()->term->create(
+			array(
+				'taxonomy' => 'wptests_tax',
+			)
+		);
+
+		$children = get_terms(
+			array(
+				'taxonomy'   => 'wptests_tax',
+				'hide_empty' => false,
+				'parent'     => $parent,
+				'fields'     => 'ids',
+			)
+		);
+
+		$this->assertEmpty( $children, 'No child terms are expected to exist.' );
+
+		$child = wp_insert_term(
+			'child-term-62031',
+			'wptests_tax',
+			array(
+				'parent' => $parent,
+			)
+		);
+
+		$children = get_terms(
+			array(
+				'taxonomy'   => 'wptests_tax',
+				'hide_empty' => false,
+				'parent'     => $parent,
+				'fields'     => 'ids',
+			)
+		);
+
+		$this->assertNotEmpty( $children, 'Child terms are expected to exist.' );
+		$this->assertContains( $child['term_id'], $children, 'Querying by parent ID is expected to include the new child term.' );
+	}
 }