diff --git a/tests/phpunit/tests/oembed/WpEmbed.php b/tests/phpunit/tests/oembed/WpEmbed.php
new file mode 100644
index 0000000000..8fe8ae661b
--- /dev/null
+++ b/tests/phpunit/tests/oembed/WpEmbed.php
@@ -0,0 +1,250 @@
+<?php
+
+/**
+ * @group oembed
+ */
+class Tests_WP_Embed extends WP_UnitTestCase {
+	/**
+	 * @var WP_Embed
+	 */
+	protected $wp_embed;
+
+	public function setUp() {
+		$this->wp_embed = new WP_Embed();
+	}
+
+	public function _embed_handler_callback( $matches, $attr, $url, $rawattr ) {
+		return sprintf( 'Embedded %s', $url );
+	}
+
+	public function _pre_oembed_result_callback() {
+		return '<b>Embedded content</b>';
+	}
+
+	public function test_maybe_run_ajax_cache_should_return_nothing_if_there_is_no_post() {
+		$this->expectOutputString('');
+		$this->wp_embed->maybe_run_ajax_cache();
+	}
+
+	public function test_maybe_run_ajax_cache_should_return_nothing_if_there_is_no_message() {
+		$GLOBALS['post'] = $this->factory()->post->create_and_get( array(
+			'post_title' => 'Hello World',
+		) );
+
+		$this->expectOutputString('');
+
+		$this->wp_embed->maybe_run_ajax_cache();
+		unset( $GLOBALS['post'] );
+	}
+
+	public function test_maybe_run_ajax_cache_should_return_javascript() {
+		$GLOBALS['post'] = $this->factory()->post->create_and_get( array(
+			'post_title' => 'Hello World',
+		) );
+		$_GET['message'] = 'foo';
+
+		$url    = admin_url( 'admin-ajax.php?action=oembed-cache&post=' . $GLOBALS['post']->ID, 'relative' );
+		$actual = get_echo( array( $this->wp_embed, 'maybe_run_ajax_cache' ) );
+
+		unset( $GLOBALS['post'] );
+		unset( $GLOBALS['message'] );
+
+		$this->assertContains( $url, $actual );
+	}
+
+	public function test_wp_maybe_load_embeds() {
+		$this->assertEqualSets( array( 10, 9999 ), array_keys( $GLOBALS['wp_embed']->handlers ) );
+		$this->assertEqualSets( array(
+			'youtube_embed_url',
+		), array_keys( $GLOBALS['wp_embed']->handlers[10] ) );
+		$this->assertEqualSets( array(
+			'audio',
+			'video',
+		), array_keys( $GLOBALS['wp_embed']->handlers[9999] ) );
+	}
+
+	public function test_wp_embed_register_handler() {
+		$handle   = rand_str();
+		$regex    = '#https?://example\.com/embed/([^/]+)#i';
+		$callback = array( $this, '_embed_handler_callback' );
+
+		wp_embed_register_handler( $handle, $regex, $callback );
+
+		$expected = array(
+			'regex'    => $regex,
+			'callback' => $callback,
+		);
+		$actual   = $GLOBALS['wp_embed']->handlers[10];
+
+		wp_embed_unregister_handler( $handle );
+
+		$this->assertContains( $expected, $actual );
+	}
+
+	public function test_wp_embed_unregister_handler() {
+		$this->assertArrayHasKey( 'youtube_embed_url', $GLOBALS['wp_embed']->handlers[10] );
+
+		wp_embed_unregister_handler( 'youtube_embed_url' );
+
+		$handlers = $GLOBALS['wp_embed']->handlers[10];
+
+		// Restore.
+		wp_embed_register_handler( 'youtube_embed_url', '#https?://(www.)?youtube\.com/(?:v|embed)/([^/]+)#i', 'wp_embed_handler_youtube' );
+
+		$this->assertArrayNotHasKey( 'youtube_embed_url', $handlers );
+	}
+
+	public function test_autoembed_should_do_nothing_without_matching_handler() {
+		$content = "\nhttp://example.com/embed/foo\n";
+
+		$actual = $this->wp_embed->autoembed( $content );
+		$this->assertEquals( $content, $actual );
+	}
+
+	public function test_autoembed_should_return_modified_content() {
+		$handle   = rand_str();
+		$regex    = '#https?://example\.com/embed/([^/]+)#i';
+		$callback = array( $this, '_embed_handler_callback' );
+
+		wp_embed_register_handler( $handle, $regex, $callback );
+
+		$content = "\nhttp://example.com/embed/foo\n";
+
+		$actual = $GLOBALS['wp_embed']->autoembed( $content );
+		wp_embed_unregister_handler( $handle );
+
+		$this->assertEquals( "\nEmbedded http://example.com/embed/foo\n", $actual );
+	}
+
+	public function test_delete_oembed_caches() {
+		$post_id = $this->factory()->post->create();
+
+		add_post_meta( $post_id, '_oembed_foo', 'bar' );
+		add_post_meta( $post_id, '_oembed_foo', 'baz' );
+		add_post_meta( $post_id, '_oembed_baz', 'foobar', true );
+
+		$this->wp_embed->delete_oembed_caches( $post_id );
+
+		$this->assertEquals( array(), get_post_meta( $post_id, '_oembed_foo' ) );
+		$this->assertEquals( array(), get_post_meta( $post_id, '_oembed_baz' ) );
+	}
+
+	public function test_cache_oembed_invalid_post_type() {
+		$post_id = $this->factory()->post->create( array( 'post_type' => 'nav_menu_item' ) );
+
+		$this->wp_embed->cache_oembed( $post_id );
+		$this->assertNotSame( $post_id, $this->wp_embed->post_ID );
+	}
+
+	public function test_cache_oembed_empty_content() {
+		$post_id = $this->factory()->post->create( array( 'post_content' => '' ) );
+
+		$this->wp_embed->cache_oembed( $post_id );
+		$this->assertNotSame( $post_id, $this->wp_embed->post_ID );
+	}
+
+	public function test_cache_oembed_for_post() {
+		$url           = 'https://example.com/';
+		$expected      = '<b>Embedded content</b>';
+		$key_suffix    = md5( $url . serialize( wp_embed_defaults( $url ) ) );
+		$cachekey      = '_oembed_' . $key_suffix;
+		$cachekey_time = '_oembed_time_' . $key_suffix;
+
+		$post_id = $this->factory()->post->create( array( 'post_content' => 'https://example.com/' ) );
+
+		add_filter( 'pre_oembed_result', array( $this, '_pre_oembed_result_callback' ) );
+		$this->wp_embed->cache_oembed( $post_id );
+		remove_filter( 'pre_oembed_result', array( $this, '_pre_oembed_result_callback' ) );
+
+		$this->assertSame( $post_id, $this->wp_embed->post_ID );
+		$this->assertEquals( $expected, get_post_meta( $post_id, $cachekey, true ) );
+		$this->assertNotEmpty( get_post_meta( $post_id, $cachekey_time, true ) );
+	}
+
+	public function test_shortcode_should_cache_data_in_post_meta_for_known_post() {
+		$GLOBALS['post'] = $this->factory()->post->create_and_get();
+		$url             = 'https://example.com/';
+		$expected        = '<b>Embedded content</b>';
+		$key_suffix      = md5( $url . serialize( wp_embed_defaults( $url ) ) );
+		$cachekey        = '_oembed_' . $key_suffix;
+		$cachekey_time   = '_oembed_time_' . $key_suffix;
+
+		add_filter( 'pre_oembed_result', array( $this, '_pre_oembed_result_callback' ) );
+		$actual = $this->wp_embed->shortcode( array(), $url );
+		remove_filter( 'pre_oembed_result', array( $this, '_pre_oembed_result_callback' ) );
+
+		$this->assertEquals( $expected, $actual );
+
+		$this->assertEquals( $expected, get_post_meta( $GLOBALS['post']->ID, $cachekey, true ) );
+		$this->assertNotEmpty( get_post_meta( $GLOBALS['post']->ID, $cachekey_time, true ) );
+
+		// Result should be cached.
+		$actual = $this->wp_embed->shortcode( array(), $url );
+		$this->assertEquals( $expected, $actual );
+	}
+
+	public function test_shortcode_should_cache_failure_in_post_meta_for_known_post() {
+		$GLOBALS['post'] = $this->factory()->post->create_and_get();
+		$url             = 'https://example.com/';
+		$expected        = '<a href="' . esc_url( $url ) . '">' . esc_html( $url ) . '</a>';
+		$key_suffix      = md5( $url . serialize( wp_embed_defaults( $url ) ) );
+		$cachekey        = '_oembed_' . $key_suffix;
+		$cachekey_time   = '_oembed_time_' . $key_suffix;
+
+		add_filter( 'pre_oembed_result', '__return_empty_string' );
+		$actual = $this->wp_embed->shortcode( array(), $url );
+		remove_filter( 'pre_oembed_result', '__return_empty_string' );
+
+		$this->assertEquals( $expected, $actual );
+
+		$this->assertEquals( '{{unknown}}', get_post_meta( $GLOBALS['post']->ID, $cachekey, true ) );
+		$this->assertEmpty( get_post_meta( $GLOBALS['post']->ID, $cachekey_time, true ) );
+
+		// Result should be cached.
+		$actual = $this->wp_embed->shortcode( array(), $url );
+		$this->assertEquals( $expected, $actual );
+	}
+
+	public function test_shortcode_should_get_url_from_src_attribute() {
+		$url    = 'http://example.com/embed/foo';
+		$actual = $this->wp_embed->shortcode( array( 'src' => $url ) );
+
+		$this->assertEquals( '<a href="' . esc_url( $url ) . '">' . esc_html( $url ) . '</a>', $actual );
+	}
+
+	public function test_shortcode_should_return_empty_string_for_missing_url() {
+		$this->assertEmpty( $this->wp_embed->shortcode( array() ) );
+	}
+
+	public function test_shortcode_should_make_link_for_unknown_url() {
+		$url    = 'http://example.com/embed/foo';
+		$actual = $this->wp_embed->shortcode( array(), $url );
+
+		$this->assertEquals( '<a href="' . esc_url( $url ) . '">' . esc_html( $url ) . '</a>', $actual );
+	}
+
+	public function test_run_shortcode_url_only() {
+		$url    = 'http://example.com/embed/foo';
+		$actual = $this->wp_embed->run_shortcode( '[embed]' . $url . '[/embed]' );
+		$this->assertEquals( '<a href="' . esc_url( $url ) . '">' . esc_html( $url ) . '</a>', $actual );
+	}
+
+	public function test_maybe_make_link() {
+		$url    = 'http://example.com/embed/foo';
+		$actual = $this->wp_embed->maybe_make_link( $url );
+
+		$this->assertEquals( '<a href="' . esc_url( $url ) . '">' . esc_html( $url ) . '</a>', $actual );
+	}
+
+	public function test_maybe_make_link_return_false_on_fail() {
+		$this->wp_embed->return_false_on_fail = true;
+		$this->assertFalse( $this->wp_embed->maybe_make_link( 'http://example.com/' ) );
+	}
+
+	public function test_maybe_make_link_do_not_link_if_unknown() {
+		$url = 'http://example.com/';
+
+		$this->wp_embed->linkifunknown = false;
+		$this->assertEquals( $url, $this->wp_embed->maybe_make_link( $url ) );
+	}
+}