diff --git a/tests/bootstrap.js b/tests/bootstrap.js
index 15c207c63..22592a0d7 100644
--- a/tests/bootstrap.js
+++ b/tests/bootstrap.js
@@ -85,13 +85,13 @@
     // List of scripts to load in compressed mode, instead of
     // requires.  Paths relative to root.
     compressedScripts: [
-      'blockly_compressed.js',
-      'blocks_compressed.js',
-      'dart_compressed.js',
-      'javascript_compressed.js',
-      'lua_compressed.js',
-      'php_compressed.js',
-      'python_compressed.js',
+      'build/blockly_compressed.js',
+      'build/blocks_compressed.js',
+      'build/dart_compressed.js',
+      'build/javascript_compressed.js',
+      'build/lua_compressed.js',
+      'build/php_compressed.js',
+      'build/python_compressed.js',
     ],
 
     // Additional scripts to be loaded after Blockly is loaded,
diff --git a/tests/mocha/test_helpers/code_generation.js b/tests/mocha/test_helpers/code_generation.js
index 4d3c0a375..82358da63 100644
--- a/tests/mocha/test_helpers/code_generation.js
+++ b/tests/mocha/test_helpers/code_generation.js
@@ -7,7 +7,7 @@
 
 goog.declareModuleId('Blockly.test.helpers.codeGeneration');
 
-const {runTestSuites} = goog.require('Blockly.test.helpers.common');
+import {runTestSuites} from './common.js';
 
 
 /**
diff --git a/tests/mocha/test_helpers/fields.js b/tests/mocha/test_helpers/fields.js
index ce69e2eb3..8d796d4a6 100644
--- a/tests/mocha/test_helpers/fields.js
+++ b/tests/mocha/test_helpers/fields.js
@@ -6,7 +6,7 @@
 
 goog.declareModuleId('Blockly.test.helpers.fields');
 
-const {runTestCases, TestCase} = goog.require('Blockly.test.helpers.common');
+import {runTestCases, TestCase} from './common.js';
 
 
 /**
diff --git a/tests/mocha/test_helpers/procedures.js b/tests/mocha/test_helpers/procedures.js
index fddd25101..a8b0f629b 100644
--- a/tests/mocha/test_helpers/procedures.js
+++ b/tests/mocha/test_helpers/procedures.js
@@ -5,7 +5,7 @@
  */
 goog.declareModuleId('Blockly.test.helpers.procedures');
 
-const {ConnectionType} = goog.require('Blockly.ConnectionType');
+import {ConnectionType} from '../../../core/connection_type.js';
 
 
 /**
diff --git a/tests/mocha/test_helpers/serialization.js b/tests/mocha/test_helpers/serialization.js
index 8aa4cc1f0..cc076bfc0 100644
--- a/tests/mocha/test_helpers/serialization.js
+++ b/tests/mocha/test_helpers/serialization.js
@@ -6,7 +6,7 @@
 
 goog.declareModuleId('Blockly.test.helpers.serialization');
 
-const {runTestCases} = goog.require('Blockly.test.helpers.common');
+import {runTestCases} from './common.js';
 
 /**
  * Serialization test case.
diff --git a/tests/mocha/test_helpers/setup_teardown.js b/tests/mocha/test_helpers/setup_teardown.js
index 3b66f7a9a..16320c5d5 100644
--- a/tests/mocha/test_helpers/setup_teardown.js
+++ b/tests/mocha/test_helpers/setup_teardown.js
@@ -6,9 +6,8 @@
 
 goog.declareModuleId('Blockly.test.helpers.setupTeardown');
 
-const eventUtils = goog.require('Blockly.Events.utils');
-const {Blocks} = goog.require('Blockly.blocks');
-
+import * as eventUtils from '../../../core/events/utils.js';
+import {Blocks} from '../../../blocks/blocks.js';
 
 /**
  * Safely disposes of Blockly workspace, logging any errors.
diff --git a/tests/mocha/test_helpers/user_input.js b/tests/mocha/test_helpers/user_input.js
index 2cae27bf1..5c8a66cd3 100644
--- a/tests/mocha/test_helpers/user_input.js
+++ b/tests/mocha/test_helpers/user_input.js
@@ -6,7 +6,7 @@
 
 goog.declareModuleId('Blockly.test.helpers.userInput');
 
-const {KeyCodes} = goog.require('Blockly.utils.KeyCodes');
+import {KeyCodes} from '../../../core/utils/keycodes.js';
 
 
 /**
diff --git a/tests/mocha/test_helpers/workspace.js b/tests/mocha/test_helpers/workspace.js
index ca1df2550..a4fbfdc35 100644
--- a/tests/mocha/test_helpers/workspace.js
+++ b/tests/mocha/test_helpers/workspace.js
@@ -6,10 +6,10 @@
 
 goog.declareModuleId('Blockly.test.helpers.workspace');
 
-const {assertVariableValues} = goog.require('Blockly.test.helpers.variables');
-const {assertWarnings} = goog.require('Blockly.test.helpers.warnings');
-const eventUtils = goog.require('Blockly.Events.utils');
-const {workspaceTeardown} = goog.require('Blockly.test.helpers.setupTeardown');
+import {assertVariableValues} from './variables.js';
+import {assertWarnings} from './warnings.js';
+import * as eventUtils from '../../../core/events/utils.js';
+import {workspaceTeardown} from './setup_teardown.js';
 
 
 export function testAWorkspace() {
diff --git a/tests/playground.html b/tests/playground.html
index 89f836055..a47720993 100644
--- a/tests/playground.html
+++ b/tests/playground.html
@@ -8,6 +8,7 @@
      compressed when it is being hosted or on Internet Explorer.  -->
 <script>
   var BLOCKLY_BOOTSTRAP_OPTIONS = {
+    loadCompressed: true,
     additionalScripts: [
       'msg/messages.js',
       'tests/playgrounds/screenshot.js',