diff --git a/tests/phpunit/tests/functions/wpuploadbits.php b/tests/phpunit/tests/functions/wpuploadbits.php
new file mode 100644
index 0000000000000..dbcb944d624ae
--- /dev/null
+++ b/tests/phpunit/tests/functions/wpuploadbits.php
@@ -0,0 +1,88 @@
+<?php
+/**
+ * Tests the wp_upload_bits() function.
+ *
+ * @group functions.php
+ * @group upload
+ *
+ * @covers ::wp_upload_bits
+ */
+
+class Tests_Functions_WpUploadBits extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 57130
+	 *
+	 * @expectedDeprecated wp_upload_bits
+	 */
+	public function test_wp_upload_bits_should_throw_Deprecated_error_if_second_parm_present_and_not_null() {
+		wp_upload_bits( 'filename.txt', 'not_null', 'bits' );
+	}
+
+	/**
+	 * Tests that wp_upload_bits() returns an array with an error message if the filename is empty.
+	 *
+	 * @ticket 57130
+	 **/
+	public function test_wp_upload_bits_should_return_an_array_with_error_message_if_no_name_present() {
+		$this->assertSameSets( array( 'error' => __( 'Empty filename' ) ), wp_upload_bits( '', '', 'bits' ) );
+	}
+
+	/**
+	 * Tests that wp_upload_bits() returns an array with an error message if the file type is not allowed.
+	 *
+	 * @ticket 57130
+	 **/
+	public function test_wp_upload_bits_should_return_an_array_with_error_message_if_filename_without_an_extension() {
+		$this->assertSameSets( array( 'error' => __( 'Sorry, you are not allowed to upload this file type.' ) ), wp_upload_bits( 'filename', '', 'bits' ) );
+	}
+
+	/**
+	 * @ticket 57130
+	 *
+	 *
+	 **/
+	public function test_should_return_error_if_bad_time_path_is_passed() {
+		$upload_dir = wp_upload_dir();
+		$this->assertSameSets(
+			array(
+				'path'    => ABSPATH . 'wp-content/uploads/.././/1',
+				'url'     => $upload_dir['baseurl'] . '/.././/1',
+				'subdir'  => '/.././/1',
+				'basedir' => ABSPATH . 'wp-content/uploads',
+				'baseurl' => $upload_dir['baseurl'],
+				'error'   => 'Unable to create directory wp-content/uploads/.././/1. Is its parent directory writable by the server?',
+			),
+			wp_upload_bits( 'filename.jpg', null, 'bits', '../../12' )
+		);
+	}
+
+	/**
+	 * Tests that wp_upload_bits() creates a file in the upload folder with the given content.
+	 *
+	 * @ticket 57130
+	 */
+	public function test_wp_upload_bits_should_create_file_in_upload_folder_with_given_content() {
+		$upload_dir = wp_upload_dir();
+		$filename   = ABSPATH . 'wp-content/uploads/9999/12/filename.txt';
+		$content    = 'file content';
+
+		$this->assertSameSets(
+			array(
+				'error' => false,
+				'path'  => $filename,
+				'url'   => $upload_dir['baseurl'] . '/9999/12/filename.txt',
+				'type'  => 'text/plain',
+
+			),
+			wp_upload_bits( 'filename.txt', null, $content, '9999/12' ),
+			'wp_upload_bits() did not return the expected result.'
+		);
+		$file          = fopen( $filename, 'rb' );
+		$file_contents = fread( $file, filesize( $filename ) );
+		fclose( $file );
+		$this->unlink( $filename );
+
+		$this->assertSame( $content, $file_contents, 'The content of the file does not match the expected value.' );
+	}
+}