diff --git a/phpunit/blocks/get-block-templates-test.php b/phpunit/blocks/get-block-templates-test.php
new file mode 100644
index 00000000000000..76c48047a3e191
--- /dev/null
+++ b/phpunit/blocks/get-block-templates-test.php
@@ -0,0 +1,109 @@
+<?php
+/**
+ * @group blocks
+ * @group block-templates
+ *
+ * @covers ::get_block_templates
+ */
+class Tests_Blocks_GetBlockTemplates extends WP_UnitTestCase {
+
+	const TEST_THEME = 'block-theme';
+
+	/**
+	 * Theme root directory.
+	 *
+	 * @var string
+	 */
+	private $theme_root;
+
+	/**
+	 * Original theme directory.
+	 *
+	 * @var string
+	 */
+	private $orig_theme_dir;
+
+	public function set_up() {
+		parent::set_up();
+		$this->theme_root      = realpath( __DIR__ . '/../data/themedir1' );
+		$this->orig_theme_dir  = $GLOBALS['wp_theme_directories'];
+
+		// /themes is necessary as theme.php functions assume /themes is the root if there is only one root.
+		$GLOBALS['wp_theme_directories'] = array( WP_CONTENT_DIR . '/themes', $this->theme_root );
+
+		add_filter( 'theme_root', array( $this, 'filter_set_theme_root' ) );
+		add_filter( 'stylesheet_root', array( $this, 'filter_set_theme_root' ) );
+		add_filter( 'template_root', array( $this, 'filter_set_theme_root' ) );
+		// Clear caches.
+		wp_clean_themes_cache();
+		unset( $GLOBALS['wp_themes'] );
+		switch_theme( self::TEST_THEME );
+	}
+
+	public function tear_down() {
+		$GLOBALS['wp_theme_directories'] = $this->orig_theme_dir;
+		wp_clean_themes_cache();
+		unset( $GLOBALS['wp_themes'] );
+		parent::tear_down();
+	}
+
+	public function filter_set_theme_root() {
+		return $this->theme_root;
+	}
+
+	/**
+	 * Gets the template IDs from the given array.
+	 *
+	 * @param object[] $templates Array of template objects to parse.
+	 * @return string[] The template IDs.
+	 */
+	private function get_template_ids( $templates ) {
+		return array_map(
+			static function ( $template ) {
+				return $template->id;
+			},
+			$templates
+		);
+	}
+
+	/**
+	 * @dataProvider data_get_block_templates_should_respect_posttypes_property
+	 * @ticket 55881
+	 *
+	 * @param string $post_type Post type for query.
+	 * @param array  $expected  Expected template IDs.
+	 */
+	public function test_get_block_templates_should_respect_posttypes_property( $post_type, $expected ) {
+		$templates = gutenberg_get_block_templates( array( 'post_type' => $post_type ) );
+
+		$this->assertSameSets(
+			$expected,
+			$this->get_template_ids( $templates )
+		);
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array
+	 */
+	public function data_get_block_templates_should_respect_posttypes_property() {
+		// @code-merge: This code will go into Core's tests/phpunit/tests/blocks/getBlockTemplates.php.
+		return array(
+			'post' => array(
+				'post_type' => 'post',
+				'expected'  => array(
+					'block-theme//custom-hero-template',
+					'block-theme//custom-single-post-template',
+				),
+			),
+			'page' => array(
+				'post_type' => 'page',
+				'expected'  => array(
+					'block-theme//custom-hero-template',
+					'block-theme//page-home',
+				),
+			),
+		);
+	}
+}
diff --git a/phpunit/data/themedir1/block-theme/templates/custom-hero-template.html b/phpunit/data/themedir1/block-theme/templates/custom-hero-template.html
new file mode 100644
index 00000000000000..0a62cda60641a1
--- /dev/null
+++ b/phpunit/data/themedir1/block-theme/templates/custom-hero-template.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+<p>Custom Hero template</p>
+<!-- /wp:paragraph -->
diff --git a/phpunit/data/themedir1/block-theme/templates/custom-single-post-template.html b/phpunit/data/themedir1/block-theme/templates/custom-single-post-template.html
new file mode 100644
index 00000000000000..fc0a5f8a4b154d
--- /dev/null
+++ b/phpunit/data/themedir1/block-theme/templates/custom-single-post-template.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+<p>Custom Single Post template</p>
+<!-- /wp:paragraph -->
diff --git a/phpunit/data/themedir1/block-theme/templates/index.html b/phpunit/data/themedir1/block-theme/templates/index.html
new file mode 100644
index 00000000000000..451c2c1a5c159b
--- /dev/null
+++ b/phpunit/data/themedir1/block-theme/templates/index.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+<p>Index Template</p>
+<!-- /wp:paragraph -->
diff --git a/phpunit/data/themedir1/block-theme/templates/page-home.html b/phpunit/data/themedir1/block-theme/templates/page-home.html
new file mode 100644
index 00000000000000..fd46fc0018fff4
--- /dev/null
+++ b/phpunit/data/themedir1/block-theme/templates/page-home.html
@@ -0,0 +1,3 @@
+<!-- wp:paragraph -->
+<p>Page (Home) Template</p>
+<!-- /wp:paragraph -->