@@ -0,0 +1,105 @@
+<?php
+
+/**
+ * Tests for term_description().
+ *
+ * @group taxonomy
+ *
+ * @covers ::term_description
+ */
+class Tests_Term_TermDescription extends WP_UnitTestCase {
+
+	/**
+	 * Category object with a description.
+	 *
+	 * @var WP_Term
+	 */
+	private static $category;
+
+	/**
+	 * Tag object with a description.
+	 *
+	 * @var WP_Term
+	 */
+	private static $tag;
+
+	/**
+	 * Creates shared category and tag fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory Test factory.
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		self::$category = $factory->category->create_and_get(
+			array(
+				'name'        => 'Described Category',
+				'slug'        => 'described-category',
+				'description' => 'Category description text',
+			)
+		);
+
+		self::$tag = $factory->tag->create_and_get(
+			array(
+				'name'        => 'Described Tag',
+				'slug'        => 'described-tag',
+				'description' => 'Tag description text',
+			)
+		);
+	}
+
+	/**
+	 * Tests that term_description() returns the formatted description for a given term ID.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_returns_description_for_term_id() {
+		$this->assertSame(
+			"<p>Category description text</p>\n",
+			term_description( self::$category->term_id )
+		);
+
+		$this->assertSame(
+			"<p>Tag description text</p>\n",
+			term_description( self::$tag->term_id )
+		);
+	}
+
+	/**
+	 * Tests that term_description() defaults to the queried object on category, tag, and custom taxonomy archives.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_defaults_to_queried_object_on_term_archives() {
+		$this->go_to( get_category_link( self::$category->term_id ) );
+		$this->assertTrue( is_category() );
+		$this->assertSame( "<p>Category description text</p>\n", term_description() );
+
+		$this->go_to( get_tag_link( self::$tag->term_id ) );
+		$this->assertTrue( is_tag() );
+		$this->assertSame( "<p>Tag description text</p>\n", term_description() );
+
+		register_taxonomy( 'wptests_tax', 'post' );
+		$custom_term = self::factory()->term->create_and_get(
+			array(
+				'taxonomy'    => 'wptests_tax',
+				'description' => 'Custom taxonomy description text',
+			)
+		);
+
+		$this->go_to( get_term_link( $custom_term, 'wptests_tax' ) );
+		$this->assertTrue( is_tax() );
+		$this->assertSame( "<p>Custom taxonomy description text</p>\n", term_description() );
+	}
+
+	/**
+	 * Tests that term_description() returns an empty string when the term does not exist
+	 * or when no term is passed outside a term archive.
+	 *
+	 * @ticket 65819
+	 */
+	public function test_returns_empty_string_for_invalid_term_or_non_term_archive() {
+		$this->assertSame( '', term_description( 99999999 ) );
+
+		$this->go_to( home_url( '/' ) );
+		$this->assertSame( '', term_description() );
+	}
+}