diff --git a/tests/deps.mocha.js b/tests/deps.mocha.js
index c43d84e13..f2d550157 100644
--- a/tests/deps.mocha.js
+++ b/tests/deps.mocha.js
@@ -44,19 +44,19 @@ goog.addDependency('../../tests/mocha/registry_test.js', ['Blockly.test.registry
 goog.addDependency('../../tests/mocha/run_mocha_tests_in_browser.js', [], [], {'lang': 'es8'});
 goog.addDependency('../../tests/mocha/serializer_test.js', ['Blockly.test.serialization'], ['Blockly.test.helpers.common', 'Blockly.test.helpers.setupTeardown'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../tests/mocha/shortcut_registry_test.js', ['Blockly.test.shortcutRegistry'], ['Blockly.test.helpers.setupTeardown', 'Blockly.test.helpers.userInput'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/block_definitions.js', ['Blockly.test.helpers.blockDefinitions'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/code_generation.js', ['Blockly.test.helpers.codeGeneration'], ['Blockly.test.helpers.common'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/common.js', ['Blockly.test.helpers.common'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/events.js', ['Blockly.test.helpers.events'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/fields.js', ['Blockly.test.helpers.fields'], ['Blockly.test.helpers.common'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/procedures.js', ['Blockly.test.helpers.procedures'], ['Blockly.ConnectionType'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/serialization.js', ['Blockly.test.helpers.serialization'], ['Blockly.test.helpers.common'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/setup_teardown.js', ['Blockly.test.helpers.setupTeardown'], ['Blockly.Events.utils', 'Blockly.blocks'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/toolbox_definitions.js', ['Blockly.test.helpers.toolboxDefinitions'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/user_input.js', ['Blockly.test.helpers.userInput'], ['Blockly.utils.KeyCodes'], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/variables.js', ['Blockly.test.helpers.variables'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/warnings.js', ['Blockly.test.helpers.warnings'], [], {'lang': 'es6', 'module': 'goog'});
-goog.addDependency('../../tests/mocha/test_helpers/workspace.js', ['Blockly.test.helpers.workspace'], ['Blockly.Events.utils', 'Blockly.test.helpers.setupTeardown', 'Blockly.test.helpers.variables', 'Blockly.test.helpers.warnings'], {'lang': 'es6', 'module': 'goog'});
+goog.addDependency('../../tests/mocha/test_helpers/block_definitions.js', ['Blockly.test.helpers.blockDefinitions'], [], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/code_generation.js', ['Blockly.test.helpers.codeGeneration'], ['Blockly.test.helpers.common'], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/common.js', ['Blockly.test.helpers.common'], [], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/events.js', ['Blockly.test.helpers.events'], [], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/fields.js', ['Blockly.test.helpers.fields'], ['Blockly.test.helpers.common'], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/procedures.js', ['Blockly.test.helpers.procedures'], ['Blockly.ConnectionType'], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/serialization.js', ['Blockly.test.helpers.serialization'], ['Blockly.test.helpers.common'], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/setup_teardown.js', ['Blockly.test.helpers.setupTeardown'], ['Blockly.Events.utils', 'Blockly.blocks'], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/toolbox_definitions.js', ['Blockly.test.helpers.toolboxDefinitions'], [], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/user_input.js', ['Blockly.test.helpers.userInput'], ['Blockly.utils.KeyCodes'], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/variables.js', ['Blockly.test.helpers.variables'], [], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/warnings.js', ['Blockly.test.helpers.warnings'], [], {'lang': 'es6', 'module': 'es6'});
+goog.addDependency('../../tests/mocha/test_helpers/workspace.js', ['Blockly.test.helpers.workspace'], ['Blockly.Events.utils', 'Blockly.test.helpers.setupTeardown', 'Blockly.test.helpers.variables', 'Blockly.test.helpers.warnings'], {'lang': 'es6', 'module': 'es6'});
 goog.addDependency('../../tests/mocha/theme_test.js', ['Blockly.test.theme'], ['Blockly.Events.utils', 'Blockly.test.helpers.events', 'Blockly.test.helpers.setupTeardown'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../tests/mocha/toolbox_test.js', ['Blockly.test.toolbox'], ['Blockly.test.helpers.blockDefinitions', 'Blockly.test.helpers.setupTeardown', 'Blockly.test.helpers.toolboxDefinitions'], {'lang': 'es6', 'module': 'goog'});
 goog.addDependency('../../tests/mocha/tooltip_test.js', ['Blockly.test.tooltip'], ['Blockly.test.helpers.setupTeardown'], {'lang': 'es6', 'module': 'goog'});
diff --git a/tests/mocha/.eslintrc.json b/tests/mocha/.eslintrc.json
index 8ebf31ae6..08eee3328 100644
--- a/tests/mocha/.eslintrc.json
+++ b/tests/mocha/.eslintrc.json
@@ -1,4 +1,7 @@
 {
+    "parserOptions": {
+      "sourceType": "module"
+    },
     "env": {
         "browser": true,
         "mocha": true
diff --git a/tests/mocha/astnode_test.js b/tests/mocha/astnode_test.js
index f974f3ea8..1a15dfb62 100644
--- a/tests/mocha/astnode_test.js
+++ b/tests/mocha/astnode_test.js
@@ -11,6 +11,7 @@ const {sharedTestSetup, sharedTestTeardown, workspaceTeardown} = goog.require('B
 
 
 suite('ASTNode', function() {
+  console.log('1/a');
   setup(function() {
     sharedTestSetup.call(this);
     Blockly.defineBlocksWithJsonArray([{
@@ -100,7 +101,9 @@ suite('ASTNode', function() {
   });
 
   suite('HelperFunctions', function() {
+    console.log('2');
     test('findNextForInput_', function() {
+      console.log('3');
       const input = this.blocks.statementInput1.inputList[0];
       const input2 = this.blocks.statementInput1.inputList[1];
       const connection = input.connection;
@@ -169,6 +172,7 @@ suite('ASTNode', function() {
   });
 
   suite('NavigationFunctions', function() {
+    console.log('b');
     setup(function() {
       Blockly.defineBlocksWithJsonArray([{
         "type": "top_connection",
@@ -319,7 +323,9 @@ suite('ASTNode', function() {
         workspaceTeardown.call(this, this.singleBlockWorkspace);
       });
 
+      console.log('c');
       test('fromPreviousToBlock', function() {
+        console.log('d');
         const prevConnection = this.blocks.statementInput1.previousConnection;
         const node = ASTNode.createConnectionNode(prevConnection);
         const nextNode = node.next();
diff --git a/tests/mocha/test_helpers/block_definitions.js b/tests/mocha/test_helpers/block_definitions.js
index a30d7defe..213075a74 100644
--- a/tests/mocha/test_helpers/block_definitions.js
+++ b/tests/mocha/test_helpers/block_definitions.js
@@ -4,10 +4,10 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.blockDefinitions');
+goog.declareModuleId('Blockly.test.helpers.blockDefinitions');
 
 
-function defineStackBlock(name = 'stack_block') {
+export function defineStackBlock(name = 'stack_block') {
   Blockly.defineBlocksWithJsonArray([{
     "type": name,
     "message0": "",
@@ -15,9 +15,8 @@ function defineStackBlock(name = 'stack_block') {
     "nextStatement": null,
   }]);
 }
-exports.defineStackBlock = defineStackBlock;
 
-function defineRowBlock(name = 'row_block') {
+export function defineRowBlock(name = 'row_block') {
   Blockly.defineBlocksWithJsonArray([{
     "type": name,
     "message0": "%1",
@@ -30,9 +29,8 @@ function defineRowBlock(name = 'row_block') {
     "output": null,
   }]);
 }
-exports.defineRowBlock = defineRowBlock;
 
-function defineStatementBlock(name = 'statement_block') {
+export function defineStatementBlock(name = 'statement_block') {
   Blockly.defineBlocksWithJsonArray([{
     "type": name,
     "message0": "%1",
@@ -49,9 +47,8 @@ function defineStatementBlock(name = 'statement_block') {
     "helpUrl": "",
   }]);
 }
-exports.defineStatementBlock = defineStatementBlock;
 
-function defineBasicBlockWithField(name = 'test_field_block') {
+export function defineBasicBlockWithField(name = 'test_field_block') {
   Blockly.defineBlocksWithJsonArray([{
     "type": name,
     "message0": "%1",
@@ -64,9 +61,8 @@ function defineBasicBlockWithField(name = 'test_field_block') {
     "output": null,
   }]);
 }
-exports.defineBasicBlockWithField = defineBasicBlockWithField;
 
-function defineMutatorBlocks() {
+export function defineMutatorBlocks() {
   Blockly.defineBlocksWithJsonArray([
     {
       'type': 'xml_block',
@@ -158,9 +154,8 @@ function defineMutatorBlocks() {
   };
   Blockly.Extensions.registerMutator('jso_mutator', jsoMutator);
 }
-exports.defineMutatorBlocks = defineMutatorBlocks;
 
-function createTestBlock() {
+export function createTestBlock() {
   return {
     'id': 'test',
     'rendered': false,
@@ -174,12 +169,10 @@ function createTestBlock() {
     'updateVarName': Blockly.Block.prototype.updateVarName,
   };
 }
-exports.createTestBlock = createTestBlock;
 
-function createRenderedBlock(workspaceSvg, type) {
+export function createRenderedBlock(workspaceSvg, type) {
   const block = workspaceSvg.newBlock(type);
   block.initSvg();
   block.render();
   return block;
 }
-exports.createRenderedBlock = createRenderedBlock;
diff --git a/tests/mocha/test_helpers/code_generation.js b/tests/mocha/test_helpers/code_generation.js
index 72d520c7f..4d3c0a375 100644
--- a/tests/mocha/test_helpers/code_generation.js
+++ b/tests/mocha/test_helpers/code_generation.js
@@ -5,7 +5,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.codeGeneration');
+goog.declareModuleId('Blockly.test.helpers.codeGeneration');
 
 const {runTestSuites} = goog.require('Blockly.test.helpers.common');
 
@@ -15,7 +15,7 @@ const {runTestSuites} = goog.require('Blockly.test.helpers.common');
  * @implements {TestCase}
  * @record
  */
-class CodeGenerationTestCase {
+export class CodeGenerationTestCase {
   /**
    * Class for a code generation test case.
    */
@@ -43,14 +43,13 @@ class CodeGenerationTestCase {
    */
   createBlock(workspace) {}
 }
-exports.CodeGenerationTestCase = CodeGenerationTestCase;
 
 /**
  * Code generation test suite.
  * @extends {TestSuite<CodeGenerationTestCase, CodeGenerationTestSuite>}
  * @record
  */
-class CodeGenerationTestSuite {
+export class CodeGenerationTestSuite {
   /**
    * Class for a code generation test suite.
    */
@@ -61,7 +60,6 @@ class CodeGenerationTestSuite {
     this.generator;
   }
 }
-exports.CodeGenerationTestSuite = CodeGenerationTestSuite;
 
 /**
  * Returns mocha test callback for code generation based on provided
@@ -102,7 +100,7 @@ const createCodeGenerationTestFn_ = (generator) => {
  * Runs blockToCode test suites.
  * @param {!Array<!CodeGenerationTestSuite>} testSuites The test suites to run.
  */
-const runCodeGenerationTestSuites = (testSuites) => {
+export const runCodeGenerationTestSuites = (testSuites) => {
   /**
    * Creates function used to generate mocha test callback.
    * @param {!CodeGenerationTestSuite} suiteInfo The test suite information.
@@ -115,4 +113,3 @@ const runCodeGenerationTestSuites = (testSuites) => {
 
   runTestSuites(testSuites, createTestFn);
 };
-exports.runCodeGenerationTestSuites = runCodeGenerationTestSuites;
diff --git a/tests/mocha/test_helpers/common.js b/tests/mocha/test_helpers/common.js
index fcb61021a..8e705b0fc 100644
--- a/tests/mocha/test_helpers/common.js
+++ b/tests/mocha/test_helpers/common.js
@@ -4,13 +4,13 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.common');
+goog.declareModuleId('Blockly.test.helpers.common');
 
 /**
  * Test case configuration.
  * @record
  */
-class TestCase {
+export class TestCase {
   /**
    * Class for a test case configuration.
    */
@@ -31,7 +31,6 @@ class TestCase {
     this.only;
   }
 }
-exports.TestCase = TestCase;
 
 /**
  * Test suite configuration.
@@ -39,7 +38,7 @@ exports.TestCase = TestCase;
  * @template {TestCase} T
  * @template {TestSuite} U
  */
-class TestSuite {
+export class TestSuite {
   /**
    * Class for a test suite configuration.
    */
@@ -68,7 +67,6 @@ class TestSuite {
     this.only;
   }
 }
-exports.TestSuite = TestSuite;
 
 /**
  * Runs provided test cases.
@@ -77,14 +75,13 @@ exports.TestSuite = TestSuite;
  * @param {function(T):Function} createTestCallback Creates test
  *    callback using given test case.
  */
-function runTestCases(testCases, createTestCallback) {
+export function runTestCases(testCases, createTestCallback) {
   testCases.forEach((testCase) => {
     let testCall = (testCase.skip ? test.skip : test);
     testCall = (testCase.only ? test.only : testCall);
     testCall(testCase.title, createTestCallback(testCase));
   });
 }
-exports.runTestCases = runTestCases;
 
 /**
  * Runs provided test suite.
@@ -95,7 +92,7 @@ exports.runTestCases = runTestCases;
  *    } createTestCaseCallback Creates test case callback using given test
  *    suite.
  */
-function runTestSuites(testSuites, createTestCaseCallback) {
+export function runTestSuites(testSuites, createTestCaseCallback) {
   testSuites.forEach((testSuite) => {
     let suiteCall = (testSuite.skip ? suite.skip : suite);
     suiteCall = (testSuite.only ? suite.only : suiteCall);
@@ -109,4 +106,3 @@ function runTestSuites(testSuites, createTestCaseCallback) {
     });
   });
 }
-exports.runTestSuites = runTestSuites;
diff --git a/tests/mocha/test_helpers/events.js b/tests/mocha/test_helpers/events.js
index e69573318..ba1b3f4f8 100644
--- a/tests/mocha/test_helpers/events.js
+++ b/tests/mocha/test_helpers/events.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.events');
+goog.declareModuleId('Blockly.test.helpers.events');
 
 
 /**
@@ -13,10 +13,9 @@ goog.module('Blockly.test.helpers.events');
  *    calls on.
  * @return {!SinonSpy} The created spy.
  */
-function createFireChangeListenerSpy(workspace) {
+export function createFireChangeListenerSpy(workspace) {
   return sinon.spy(workspace, 'fireChangeListener');
 }
-exports.createFireChangeListenerSpy = createFireChangeListenerSpy;
 
 /**
  * Asserts whether the given xml property has the expected property.
@@ -75,7 +74,7 @@ function isXmlProperty_(key) {
  * @param {boolean=} [isUiEvent=false] Whether the event is a UI event.
  * @param {string=} message Optional message to prepend assert messages.
  */
-function assertEventEquals(event, expectedType,
+export function assertEventEquals(event, expectedType,
     expectedWorkspaceId, expectedBlockId, expectedProperties, isUiEvent = false, message) {
   let prependMessage = message ? message + ' ' : '';
   prependMessage += 'Event fired ';
@@ -107,7 +106,6 @@ function assertEventEquals(event, expectedType,
     chai.assert.isFalse(event.isUiEvent);
   }
 }
-exports.assertEventEquals = assertEventEquals;
 
 /**
  * Asserts that an event with the given values was fired.
@@ -119,7 +117,7 @@ exports.assertEventEquals = assertEventEquals;
  * @param {string} expectedWorkspaceId Expected workspace id of event fired.
  * @param {?string=} expectedBlockId Expected block id of event fired.
  */
-function assertEventFired(spy, instanceType, expectedProperties,
+export function assertEventFired(spy, instanceType, expectedProperties,
     expectedWorkspaceId, expectedBlockId) {
   expectedProperties = Object.assign({
     workspaceId: expectedWorkspaceId,
@@ -129,7 +127,6 @@ function assertEventFired(spy, instanceType, expectedProperties,
       sinon.match.instanceOf(instanceType).and(sinon.match(expectedProperties));
   sinon.assert.calledWith(spy, expectedEvent);
 }
-exports.assertEventFired = assertEventFired;
 
 /**
  * Asserts that an event with the given values was not fired.
@@ -141,7 +138,7 @@ exports.assertEventFired = assertEventFired;
  * @param {string=} expectedWorkspaceId Expected workspace id of event fired.
  * @param {?string=} expectedBlockId Expected block id of event fired.
  */
-function assertEventNotFired(spy, instanceType, expectedProperties,
+export function assertEventNotFired(spy, instanceType, expectedProperties,
     expectedWorkspaceId, expectedBlockId) {
   expectedProperties.type = instanceType.prototype.type;
   if (expectedWorkspaceId !== undefined) {
@@ -154,7 +151,6 @@ function assertEventNotFired(spy, instanceType, expectedProperties,
       sinon.match.instanceOf(instanceType).and(sinon.match(expectedProperties));
   sinon.assert.neverCalledWith(spy, expectedEvent);
 }
-exports.assertEventNotFired = assertEventNotFired;
 
 /**
  * Filters out xml properties from given object based on key.
@@ -189,7 +185,7 @@ function splitByXmlProperties_(properties) {
  * @param {string} expectedWorkspaceId Expected workspace id of event fired.
  * @param {?string=} expectedBlockId Expected block id of event fired.
  */
-function assertNthCallEventArgEquals(spy, n, instanceType, expectedProperties,
+export function assertNthCallEventArgEquals(spy, n, instanceType, expectedProperties,
     expectedWorkspaceId, expectedBlockId) {
   const nthCall = spy.getCall(n);
   const splitProperties = splitByXmlProperties_(expectedProperties);
@@ -201,4 +197,3 @@ function assertNthCallEventArgEquals(spy, n, instanceType, expectedProperties,
   const eventArg = nthCall.firstArg;
   assertXmlProperties_(eventArg, xmlProperties);
 }
-exports.assertNthCallEventArgEquals = assertNthCallEventArgEquals;
diff --git a/tests/mocha/test_helpers/fields.js b/tests/mocha/test_helpers/fields.js
index dd89e55fa..ce69e2eb3 100644
--- a/tests/mocha/test_helpers/fields.js
+++ b/tests/mocha/test_helpers/fields.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.fields');
+goog.declareModuleId('Blockly.test.helpers.fields');
 
 const {runTestCases, TestCase} = goog.require('Blockly.test.helpers.common');
 
@@ -14,7 +14,7 @@ const {runTestCases, TestCase} = goog.require('Blockly.test.helpers.common');
  * @implements {TestCase}
  * @record
  */
-class FieldValueTestCase {
+export class FieldValueTestCase {
   /**
    * Class for a a field value test case.
    */
@@ -39,14 +39,13 @@ class FieldValueTestCase {
     this.errMsgMatcher;
   }
 }
-exports.FieldValueTestCase = FieldValueTestCase;
 
 /**
  * Field creation test case.
  * @extends {FieldValueTestCase}
  * @record
  */
-class FieldCreationTestCase {
+export class FieldCreationTestCase {
   /**
    * Class for a field creation test case.
    */
@@ -61,7 +60,6 @@ class FieldCreationTestCase {
     this.json;
   }
 }
-exports.FieldCreationTestCase = FieldCreationTestCase;
 
 /**
  * Assert a field's value is the same as the expected value.
@@ -69,7 +67,7 @@ exports.FieldCreationTestCase = FieldCreationTestCase;
  * @param {*} expectedValue The expected value.
  * @param {string=} expectedText The expected text.
  */
-function assertFieldValue(field, expectedValue, expectedText = undefined) {
+export function assertFieldValue(field, expectedValue, expectedText = undefined) {
   const actualValue = field.getValue();
   const actualText = field.getText();
   if (expectedText === undefined) {
@@ -78,7 +76,6 @@ function assertFieldValue(field, expectedValue, expectedText = undefined) {
   chai.assert.equal(actualValue, expectedValue, 'Value');
   chai.assert.equal(actualText, expectedText, 'Text');
 }
-exports.assertFieldValue = assertFieldValue;
 
 /**
  * Runs provided creation test cases.
@@ -145,7 +142,7 @@ function runCreationTestsAssertThrows_(testCases, creation) {
  * @param {function(!FieldCreationTestCase=)=} customCreateWithJs Custom
  *    creation function to use in tests.
  */
-function runConstructorSuiteTests(TestedField, validValueTestCases,
+export function runConstructorSuiteTests(TestedField, validValueTestCases,
     invalidValueTestCases, validRunAssertField, assertFieldDefault,
     customCreateWithJs) {
   suite('Constructor', function() {
@@ -182,7 +179,6 @@ function runConstructorSuiteTests(TestedField, validValueTestCases,
     runCreationTests_(validValueTestCases, validRunAssertField, createWithJs);
   });
 }
-exports.runConstructorSuiteTests = runConstructorSuiteTests;
 
 /**
  * Runs suite of tests for fromJson creation of specified field.
@@ -200,7 +196,7 @@ exports.runConstructorSuiteTests = runConstructorSuiteTests;
  * @param {function(!FieldCreationTestCase=)=} customCreateWithJson Custom
  *    creation function to use in tests.
  */
-function runFromJsonSuiteTests(TestedField, validValueTestCases,
+export function runFromJsonSuiteTests(TestedField, validValueTestCases,
     invalidValueTestCases, validRunAssertField, assertFieldDefault,
     customCreateWithJson) {
   suite('fromJson', function() {
@@ -237,7 +233,6 @@ function runFromJsonSuiteTests(TestedField, validValueTestCases,
     runCreationTests_(validValueTestCases, validRunAssertField, createWithJson);
   });
 }
-exports.runFromJsonSuiteTests = runFromJsonSuiteTests;
 
 /**
  * Runs tests for setValue calls.
@@ -250,7 +245,7 @@ exports.runFromJsonSuiteTests = runFromJsonSuiteTests;
  * @param {string=} invalidRunExpectedText Expected text for field after invalid
  *    call to setValue.
  */
-function runSetValueTests(validValueTestCases, invalidValueTestCases,
+export function runSetValueTests(validValueTestCases, invalidValueTestCases,
     invalidRunExpectedValue, invalidRunExpectedText) {
   /**
    * Creates test callback for invalid setValue test.
@@ -279,4 +274,3 @@ function runSetValueTests(validValueTestCases, invalidValueTestCases,
   runTestCases(invalidValueTestCases, createInvalidSetValueTestCallback);
   runTestCases(validValueTestCases, createValidSetValueTestCallback);
 }
-exports.runSetValueTests = runSetValueTests;
diff --git a/tests/mocha/test_helpers/procedures.js b/tests/mocha/test_helpers/procedures.js
index 6978e283e..68c7f2f3d 100644
--- a/tests/mocha/test_helpers/procedures.js
+++ b/tests/mocha/test_helpers/procedures.js
@@ -3,7 +3,7 @@
  * Copyright 2020 Google LLC
  * SPDX-License-Identifier: Apache-2.0
  */
-goog.module('Blockly.test.helpers.procedures');
+goog.declareModuleId('Blockly.test.helpers.procedures');
 
 const {ConnectionType} = goog.require('Blockly.ConnectionType');
 
@@ -55,7 +55,7 @@ function assertCallBlockArgsStructure(callBlock, args) {
  * @param {boolean=} hasStatements If we expect the procedure def to have a
  *     statement input or not.
  */
-function assertDefBlockStructure(defBlock, hasReturn = false,
+export function assertDefBlockStructure(defBlock, hasReturn = false,
     args = [], varIds = [], hasStatements = true) {
   if (hasStatements) {
     chai.assert.isNotNull(defBlock.getInput('STACK'),
@@ -82,7 +82,6 @@ function assertDefBlockStructure(defBlock, hasReturn = false,
   chai.assert.sameOrderedMembers(defBlock.getVars(), args);
   assertBlockVarModels(defBlock, varIds);
 }
-exports.assertDefBlockStructure = assertDefBlockStructure;
 
 /**
  * Asserts that the procedure definition block has the expected inputs and
@@ -91,7 +90,7 @@ exports.assertDefBlockStructure = assertDefBlockStructure;
  * @param {Array<string>=} args An array of argument names.
  * @param {Array<string>=} varIds An array of variable ids.
  */
-function assertCallBlockStructure(callBlock, args = [], varIds = []) {
+export function assertCallBlockStructure(callBlock, args = [], varIds = []) {
   if (args.length) {
     chai.assert.include(callBlock.toString(), 'with');
   } else {
@@ -101,7 +100,6 @@ function assertCallBlockStructure(callBlock, args = [], varIds = []) {
   assertCallBlockArgsStructure(callBlock, args);
   assertBlockVarModels(callBlock, varIds);
 }
-exports.assertCallBlockStructure = assertCallBlockStructure;
 
 /**
  * Creates procedure definition block using domToBlock call.
@@ -111,7 +109,7 @@ exports.assertCallBlockStructure = assertCallBlockStructure;
  * @param {Array<string>=} args An array of argument names.
  * @return {Blockly.Block} The created block.
  */
-function createProcDefBlock(
+export function createProcDefBlock(
     workspace, hasReturn = false, args = []) {
   const type = hasReturn ?
       'procedures_defreturn' : 'procedures_defnoreturn';
@@ -125,7 +123,6 @@ function createProcDefBlock(
       '</block>';
   return Blockly.Xml.domToBlock(Blockly.Xml.textToDom(xml), workspace);
 }
-exports.createProcDefBlock = createProcDefBlock;
 
 /**
  * Creates procedure call block using domToBlock call.
@@ -134,7 +131,7 @@ exports.createProcDefBlock = createProcDefBlock;
  *    has return.
  * @return {Blockly.Block} The created block.
  */
-function createProcCallBlock(
+export function createProcCallBlock(
     workspace, hasReturn = false) {
   const type = hasReturn ?
       'procedures_callreturn' : 'procedures_callnoreturn';
@@ -144,4 +141,3 @@ function createProcCallBlock(
       '</block>'
   ), workspace);
 }
-exports.createProcCallBlock = createProcCallBlock;
diff --git a/tests/mocha/test_helpers/serialization.js b/tests/mocha/test_helpers/serialization.js
index c8b90ba7f..8aa4cc1f0 100644
--- a/tests/mocha/test_helpers/serialization.js
+++ b/tests/mocha/test_helpers/serialization.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.serialization');
+goog.declareModuleId('Blockly.test.helpers.serialization');
 
 const {runTestCases} = goog.require('Blockly.test.helpers.common');
 
@@ -13,7 +13,7 @@ const {runTestCases} = goog.require('Blockly.test.helpers.common');
  * @implements {TestCase}
  * @record
  */
-class SerializationTestCase {
+export class SerializationTestCase {
   /**
    * Class for a block serialization test case.
    */
@@ -45,13 +45,12 @@ class SerializationTestCase {
    */
   assertBlockStructure(block) {}
 }
-exports.SerializationTestCase = SerializationTestCase;
 
 /**
  * Runs serialization test suite.
  * @param {!Array<!SerializationTestCase>} testCases The test cases to run.
  */
-const runSerializationTestSuite = (testCases) => {
+export const runSerializationTestSuite = (testCases) => {
   /**
    * Creates test callback for xmlToBlock test.
    * @param {!SerializationTestCase} testCase The test case information.
@@ -129,4 +128,3 @@ const runSerializationTestSuite = (testCases) => {
     });
   });
 };
-exports.runSerializationTestSuite = runSerializationTestSuite;
diff --git a/tests/mocha/test_helpers/setup_teardown.js b/tests/mocha/test_helpers/setup_teardown.js
index e1b085be1..3b66f7a9a 100644
--- a/tests/mocha/test_helpers/setup_teardown.js
+++ b/tests/mocha/test_helpers/setup_teardown.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.setupTeardown');
+goog.declareModuleId('Blockly.test.helpers.setupTeardown');
 
 const eventUtils = goog.require('Blockly.Events.utils');
 const {Blocks} = goog.require('Blockly.blocks');
@@ -16,7 +16,7 @@ const {Blocks} = goog.require('Blockly.blocks');
  * using workspaceTeardown.call(this).
  * @param {!Blockly.Workspace} workspace The workspace to dispose.
  */
-function workspaceTeardown(workspace) {
+export function workspaceTeardown(workspace) {
   try {
     this.clock.runAll();  // Run all queued setTimeout calls.
     workspace.dispose();
@@ -26,7 +26,6 @@ function workspaceTeardown(workspace) {
     console.error(testRef.fullTitle() + '\n', e);
   }
 }
-exports.workspaceTeardown = workspaceTeardown;
 
 /**
  * Creates stub for Blockly.Events.fire that advances the clock forward after
@@ -53,10 +52,9 @@ function createEventsFireStubFireImmediately_(clock) {
  *    sharedTestSetup.
  * @param {string} message The message to add to shared cleanup object.
  */
-function addMessageToCleanup(sharedCleanupObj, message) {
+export function addMessageToCleanup(sharedCleanupObj, message) {
   sharedCleanupObj.messagesCleanup_.push(message);
 }
-exports.addMessageToCleanup = addMessageToCleanup;
 
 /**
  * Adds block type to shared cleanup object so that it is cleaned from
@@ -65,10 +63,9 @@ exports.addMessageToCleanup = addMessageToCleanup;
  *    sharedTestSetup.
  * @param {string} blockType The block type to add to shared cleanup object.
  */
-function addBlockTypeToCleanup(sharedCleanupObj, blockType) {
+export function addBlockTypeToCleanup(sharedCleanupObj, blockType) {
   sharedCleanupObj.blockTypesCleanup_.push(blockType);
 }
-exports.addBlockTypeToCleanup = addBlockTypeToCleanup;
 
 /**
  * Wraps Blockly.defineBlocksWithJsonArray using stub in order to keep track of
@@ -111,7 +108,7 @@ function wrapDefineBlocksWithJsonArrayWithCleanup_(sharedCleanupObj) {
  * @param {Object<string, boolean>} options Options to enable/disable setup
  *    of certain stubs.
  */
-function sharedTestSetup(options = {}) {
+export function sharedTestSetup(options = {}) {
   this.sharedSetupCalled_ = true;
   // Sandbox created for greater control when certain stubs are cleared.
   this.sharedSetupSandbox_ = sinon.createSandbox();
@@ -128,14 +125,13 @@ function sharedTestSetup(options = {}) {
   this.messagesCleanup_ = this.sharedCleanup.messagesCleanup_;
   wrapDefineBlocksWithJsonArrayWithCleanup_(this.sharedCleanup);
 }
-exports.sharedTestSetup = sharedTestSetup;
 
 /**
  * Shared cleanup method that clears up pending setTimeout calls, disposes of
  * workspace, and resets global variables. Should be called in setup of
  * outermost suite using sharedTestTeardown.call(this).
  */
-function sharedTestTeardown() {
+export function sharedTestTeardown() {
   const testRef = this.currentTest || this.test;
   if (!this.sharedSetupCalled_) {
     console.error('"' + testRef.fullTitle() + '" did not call sharedTestSetup');
@@ -183,7 +179,6 @@ function sharedTestTeardown() {
     Blockly.WidgetDiv.testOnly_setDiv(null);
   }
 }
-exports.sharedTestTeardown = sharedTestTeardown;
 
 /**
  * Creates stub for Blockly.utils.genUid that returns the provided id or ids.
@@ -194,7 +189,7 @@ exports.sharedTestTeardown = sharedTestTeardown;
  *    that value.
  * @return {!SinonStub} The created stub.
  */
-function createGenUidStubWithReturns(returnIds) {
+export function createGenUidStubWithReturns(returnIds) {
   const stub = sinon.stub(Blockly.utils.idGenerator.TEST_ONLY, "genUid");
   if (Array.isArray(returnIds)) {
     for (let i = 0; i < returnIds.length; i++) {
@@ -205,4 +200,3 @@ function createGenUidStubWithReturns(returnIds) {
   }
   return stub;
 }
-exports.createGenUidStubWithReturns = createGenUidStubWithReturns;
diff --git a/tests/mocha/test_helpers/toolbox_definitions.js b/tests/mocha/test_helpers/toolbox_definitions.js
index ee7ff576f..0a7f2b9ef 100644
--- a/tests/mocha/test_helpers/toolbox_definitions.js
+++ b/tests/mocha/test_helpers/toolbox_definitions.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.toolboxDefinitions');
+goog.declareModuleId('Blockly.test.helpers.toolboxDefinitions');
 
 
 /**
@@ -12,7 +12,7 @@ goog.module('Blockly.test.helpers.toolboxDefinitions');
  * @return {Blockly.utils.toolbox.ToolboxJson} The array holding information
  *    for a toolbox.
  */
-function getCategoryJSON() {
+export function getCategoryJSON() {
   return {"contents": [
     {
       "kind": "CATEGORY",
@@ -42,14 +42,13 @@ function getCategoryJSON() {
       "name": "Second",
     }]};
 }
-exports.getCategoryJSON = getCategoryJSON;
 
 /**
  * Get JSON for a simple toolbox.
  * @return {Blockly.utils.toolbox.ToolboxJson} The array holding information
  *    for a simple toolbox.
  */
-function getSimpleJson() {
+export function getSimpleJson() {
   return {"contents": [
     {
       "kind": "BLOCK",
@@ -83,9 +82,8 @@ function getSimpleJson() {
     },
   ]};
 }
-exports.getSimpleJson = getSimpleJson;
 
-function getProperSimpleJson() {
+export function getProperSimpleJson() {
   return {
     "contents": [
       {
@@ -128,14 +126,13 @@ function getProperSimpleJson() {
       },
     ]};
 }
-exports.getProperSimpleJson = getProperSimpleJson;
 
 /**
  * Get JSON for a toolbox that contains categories that contain categories.
  * @return {Blockly.utils.toolbox.ToolboxJson} The array holding information
  *    for a toolbox.
  */
-function getDeeplyNestedJSON() {
+export function getDeeplyNestedJSON() {
   return {"contents": [
     {
       "kind": "CATEGORY",
@@ -173,13 +170,12 @@ function getDeeplyNestedJSON() {
       "name": "Second",
     }]};
 }
-exports.getDeeplyNestedJSON = getDeeplyNestedJSON;
 
 /**
  * Get an array filled with xml elements.
  * @return {Array<Node>} Array holding xml elements for a toolbox.
  */
-function getXmlArray() {
+export function getXmlArray() {
   const block = Blockly.Xml.textToDom(
       `<block type="logic_compare">
         <field name="OP">NEQ</field>
@@ -199,9 +195,8 @@ function getXmlArray() {
   const label = Blockly.Xml.textToDom('<label text="tooltips"></label>');
   return [block, separator, button, label];
 }
-exports.getXmlArray = getXmlArray;
 
-function getInjectedToolbox() {
+export function getInjectedToolbox() {
   /**
    * Category: First
    *   sep
@@ -221,18 +216,16 @@ function getInjectedToolbox() {
       });
   return workspace.getToolbox();
 }
-exports.getInjectedToolbox = getInjectedToolbox;
 
-function getBasicToolbox() {
+export function getBasicToolbox() {
   const workspace = new Blockly.WorkspaceSvg(new Blockly.Options({}));
   const toolbox = new Blockly.Toolbox(workspace);
   toolbox.HtmlDiv = document.createElement('div');
   toolbox.flyout_ = sinon.createStubInstance(Blockly.VerticalFlyout);
   return toolbox;
 }
-exports.getBasicToolbox = getBasicToolbox;
 
-function getCollapsibleItem(toolbox) {
+export function getCollapsibleItem(toolbox) {
   const contents = toolbox.contents_;
   for (let i = 0; i < contents.length; i++) {
     const item = contents[i];
@@ -241,9 +234,8 @@ function getCollapsibleItem(toolbox) {
     }
   }
 }
-exports.getCollapsibleItem = getCollapsibleItem;
 
-function getNonCollapsibleItem(toolbox) {
+export function getNonCollapsibleItem(toolbox) {
   const contents = toolbox.contents_;
   for (let i = 0; i < contents.length; i++) {
     const item = contents[i];
@@ -252,14 +244,11 @@ function getNonCollapsibleItem(toolbox) {
     }
   }
 }
-exports.getNonCollapsibleItem = getNonCollapsibleItem;
 
-function getChildItem(toolbox) {
+export function getChildItem(toolbox) {
   return toolbox.getToolboxItemById('nestedCategory');
 }
-exports.getChildItem = getChildItem;
 
-function getSeparator(toolbox) {
+export function getSeparator(toolbox) {
   return toolbox.getToolboxItemById('separator');
 }
-exports.getSeparator = getSeparator;
diff --git a/tests/mocha/test_helpers/user_input.js b/tests/mocha/test_helpers/user_input.js
index 9482a7909..2cae27bf1 100644
--- a/tests/mocha/test_helpers/user_input.js
+++ b/tests/mocha/test_helpers/user_input.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.userInput');
+goog.declareModuleId('Blockly.test.helpers.userInput');
 
 const {KeyCodes} = goog.require('Blockly.utils.KeyCodes');
 
@@ -17,7 +17,7 @@ const {KeyCodes} = goog.require('Blockly.utils.KeyCodes');
  * @param {Object<string, string>=} properties Properties to pass into event
  *    constructor.
  */
-function dispatchPointerEvent(target, type, properties) {
+export function dispatchPointerEvent(target, type, properties) {
   const eventInitDict = {
     cancelable: true,
     bubbles: true,
@@ -32,7 +32,6 @@ function dispatchPointerEvent(target, type, properties) {
   const event = new PointerEvent(type, eventInitDict);
   target.dispatchEvent(event);
 }
-exports.dispatchPointerEvent = dispatchPointerEvent;
 
 /**
  * Creates a key down event used for testing.
@@ -40,7 +39,7 @@ exports.dispatchPointerEvent = dispatchPointerEvent;
  * @param {!Array<number>=} modifiers A list of modifiers. Use Blockly.utils.KeyCodes enum.
  * @return {!KeyboardEvent} The mocked keydown event.
  */
-function createKeyDownEvent(keyCode, modifiers) {
+export function createKeyDownEvent(keyCode, modifiers) {
   const event = {
     keyCode: keyCode,
   };
@@ -52,7 +51,6 @@ function createKeyDownEvent(keyCode, modifiers) {
   }
   return new KeyboardEvent('keydown', event);
 }
-exports.createKeyDownEvent = createKeyDownEvent;
 
 /**
  * Simulates mouse click by triggering relevant mouse events.
@@ -60,9 +58,8 @@ exports.createKeyDownEvent = createKeyDownEvent;
  * @param {Object<string, string>=} properties Properties to pass into event
  *    constructor.
  */
-function simulateClick(target, properties) {
+export function simulateClick(target, properties) {
   dispatchPointerEvent(target, 'pointerdown', properties);
   dispatchPointerEvent(target, 'pointerup', properties);
   dispatchPointerEvent(target, 'click', properties);
 }
-exports.simulateClick = simulateClick;
diff --git a/tests/mocha/test_helpers/variables.js b/tests/mocha/test_helpers/variables.js
index f550e960b..e75047c06 100644
--- a/tests/mocha/test_helpers/variables.js
+++ b/tests/mocha/test_helpers/variables.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.variables');
+goog.declareModuleId('Blockly.test.helpers.variables');
 
 
 /**
@@ -15,11 +15,10 @@ goog.module('Blockly.test.helpers.variables');
  * @param {!string} type The expected type of the variable.
  * @param {!string} id The expected id of the variable.
  */
-function assertVariableValues(container, name, type, id) {
+export function assertVariableValues(container, name, type, id) {
   const variable = container.getVariableById(id);
   chai.assert.isDefined(variable);
   chai.assert.equal(variable.name, name);
   chai.assert.equal(variable.type, type);
   chai.assert.equal(variable.getId(), id);
 }
-exports.assertVariableValues = assertVariableValues;
diff --git a/tests/mocha/test_helpers/warnings.js b/tests/mocha/test_helpers/warnings.js
index 0457395cc..4d8658573 100644
--- a/tests/mocha/test_helpers/warnings.js
+++ b/tests/mocha/test_helpers/warnings.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.warnings');
+goog.declareModuleId('Blockly.test.helpers.warnings');
 
 
 /**
@@ -13,7 +13,7 @@ goog.module('Blockly.test.helpers.warnings');
  * @param {Function} innerFunc The function where warnings may called.
  * @return {Array<string>} The warning messages (only the first arguments).
  */
-function captureWarnings(innerFunc) {
+export function captureWarnings(innerFunc) {
   const msgs = [];
   const nativeConsoleWarn = console.warn;
   try {
@@ -26,7 +26,6 @@ function captureWarnings(innerFunc) {
   }
   return msgs;
 }
-exports.captureWarnings = captureWarnings;
 
 /**
  * Asserts that the given function logs the provided warning messages.
@@ -34,7 +33,7 @@ exports.captureWarnings = captureWarnings;
  * @param {Array<!RegExp>|!RegExp} messages A list of regex for the expected
  *    messages (in the expected order).
  */
-function assertWarnings(innerFunc, messages) {
+export function assertWarnings(innerFunc, messages) {
   if (!Array.isArray(messages)) {
     messages = [messages];
   }
@@ -44,25 +43,22 @@ function assertWarnings(innerFunc, messages) {
     chai.assert.match(warnings[i], message);
   });
 }
-exports.assertWarnings = assertWarnings;
 
 /**
  * Asserts that the given function logs no warning messages.
  * @param {function()} innerFunc The function to call.
  */
-function assertNoWarnings(innerFunc) {
+export function assertNoWarnings(innerFunc) {
   assertWarnings(innerFunc, []);
 }
-exports.assertNoWarnings = assertNoWarnings;
 
 /**
  * Stubs Blockly.utils.deprecation.warn call.
  * @return {!SinonStub} The created stub.
  */
-function createDeprecationWarningStub() {
+export function createDeprecationWarningStub() {
   return sinon.stub(Blockly.utils.deprecation, 'warn');
 }
-exports.createDeprecationWarningStub = createDeprecationWarningStub;
 
 /**
  * Asserts whether the given deprecation warning stub or call was called with
@@ -71,10 +67,9 @@ exports.createDeprecationWarningStub = createDeprecationWarningStub;
  * @param {string} functionName The function name to check that the given spy or
  *    spy call was called with.
  */
-function assertDeprecationWarningCall(spyOrSpyCall, functionName) {
+export function assertDeprecationWarningCall(spyOrSpyCall, functionName) {
   sinon.assert.calledWith(spyOrSpyCall, functionName);
 }
-exports.assertDeprecationWarningCall = assertDeprecationWarningCall;
 
 /**
  * Asserts that there was a single deprecation warning call with the given
@@ -83,8 +78,7 @@ exports.assertDeprecationWarningCall = assertDeprecationWarningCall;
  * @param {string} functionName The function name to check that the given spy
  *    was called with.
  */
-function assertSingleDeprecationWarningCall(spy, functionName) {
+export function assertSingleDeprecationWarningCall(spy, functionName) {
   sinon.assert.calledOnce(spy);
   assertDeprecationWarningCall(spy.getCall(0), functionName);
 }
-exports.assertSingleDeprecationWarningCall = assertSingleDeprecationWarningCall;
diff --git a/tests/mocha/test_helpers/workspace.js b/tests/mocha/test_helpers/workspace.js
index 204a46df6..ca1df2550 100644
--- a/tests/mocha/test_helpers/workspace.js
+++ b/tests/mocha/test_helpers/workspace.js
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-goog.module('Blockly.test.helpers.workspace');
+goog.declareModuleId('Blockly.test.helpers.workspace');
 
 const {assertVariableValues} = goog.require('Blockly.test.helpers.variables');
 const {assertWarnings} = goog.require('Blockly.test.helpers.warnings');
@@ -12,7 +12,7 @@ const eventUtils = goog.require('Blockly.Events.utils');
 const {workspaceTeardown} = goog.require('Blockly.test.helpers.setupTeardown');
 
 
-function testAWorkspace() {
+export function testAWorkspace() {
   setup(function() {
     Blockly.defineBlocksWithJsonArray([{
       "type": "get_var_block",
@@ -1528,4 +1528,3 @@ function testAWorkspace() {
     });
   });
 }
-exports.testAWorkspace = testAWorkspace;