diff --git a/tests/mocha/test_helpers/block_test_helpers.mocha.js b/tests/mocha/test_helpers/block_test_helpers.mocha.js
index 73a52c986..a8f77a8ca 100644
--- a/tests/mocha/test_helpers/block_test_helpers.mocha.js
+++ b/tests/mocha/test_helpers/block_test_helpers.mocha.js
@@ -126,11 +126,11 @@ const createCodeGenerationTestFn_ = (generator) => {
         }
       }
       const assertFunc = (typeof testCase.expectedCode === 'string') ?
-          assert.equal : assert.match;
+          chai.assert.equal : chai.assert.match;
       assertFunc(code, testCase.expectedCode);
       if (!testCase.useWorkspaceToCode &&
           testCase.expectedInnerOrder !== undefined) {
-        assert.equal(innerOrder, testCase.expectedInnerOrder);
+        chai.assert.equal(innerOrder, testCase.expectedInnerOrder);
       }
     };
   };
@@ -190,7 +190,7 @@ const runSerializationTestSuite = (testCases) => {
             testCase.json, this.workspace);
         const generatedJson = Blockly.serialization.blocks.save(block);
         const expectedJson = testCase.expectedJson || testCase.json;
-        assert.deepEqual(generatedJson, expectedJson);
+        chai.assert.deepEqual(generatedJson, expectedJson);
       } else {
         const block = Blockly.Xml.domToBlock(Blockly.Xml.textToDom(
             testCase.xml), this.workspace);
@@ -198,7 +198,7 @@ const runSerializationTestSuite = (testCases) => {
             Blockly.Xml.domToPrettyText(
                 Blockly.Xml.blockToDom(block));
         const expectedXml = testCase.expectedXml || testCase.xml;
-        assert.equal(generatedXml, expectedXml);
+        chai.assert.equal(generatedXml, expectedXml);
       }
     };
   };
diff --git a/tests/mocha/test_helpers/field_test_helpers.mocha.js b/tests/mocha/test_helpers/field_test_helpers.mocha.js
index f99a30b8c..fda26b150 100644
--- a/tests/mocha/test_helpers/field_test_helpers.mocha.js
+++ b/tests/mocha/test_helpers/field_test_helpers.mocha.js
@@ -75,9 +75,10 @@ function assertFieldValue(field, expectedValue, expectedText = undefined) {
   if (expectedText === undefined) {
     expectedText = String(expectedValue);
   }
-  assert.equal(actualValue, expectedValue, 'Value');
-  assert.equal(actualText, expectedText, 'Text');
+  chai.assert.equal(actualValue, expectedValue, 'Value');
+  chai.assert.equal(actualText, expectedText, 'Text');
 }
+exports.assertFieldValue = assertFieldValue;
 
 /**
  * Runs provided creation test cases.
@@ -120,7 +121,7 @@ function runCreationTestsAssertThrows_(testCases, creation) {
    */
   const createTestFn = (testCase) => {
     return function() {
-      assert.throws(function() {
+      chai.assert.throws(function() {
         creation.call(this, testCase);
       }, testCase.errMsgMatcher);
     };
@@ -156,7 +157,7 @@ function runConstructorSuiteTests(TestedField, validValueTestCases,
       });
     } else {
       test('Empty', function() {
-        assert.throws(function() {
+        chai.assert.throws(function() {
           customCreateWithJs ? customCreateWithJs.call(this) :
               new TestedField();
         });
@@ -211,7 +212,7 @@ function runFromJsonSuiteTests(TestedField, validValueTestCases,
       });
     } else {
       test('Empty', function() {
-        assert.throws(function() {
+        chai.assert.throws(function() {
           customCreateWithJson ? customCreateWithJson.call(this) :
               TestedField.fromJson({});
         });
diff --git a/tests/node/run_node_test.js b/tests/node/run_node_test.js
index 69d095d51..c0c428c0c 100644
--- a/tests/node/run_node_test.js
+++ b/tests/node/run_node_test.js
@@ -38,7 +38,7 @@ suite('Test Node.js', function() {
     const headlessXml = Blockly.Xml.workspaceToDom(workspace, true);
     const headlessText = Blockly.Xml.domToPrettyText(headlessXml);
 
-    assert.equal(headlessText, xmlText, 'equal');
+    chai.assert.equal(headlessText, xmlText, 'equal');
   });
   test('Generate Code', function() {
     const xml = Blockly.Xml.textToDom(xmlText);
@@ -51,7 +51,7 @@ suite('Test Node.js', function() {
     const code = Blockly.JavaScript.workspaceToCode(workspace);
 
     // Check output
-    assert.equal('window.alert(\'Hello from Blockly!\');', code.trim(), 'equal');
+    chai.assert.equal('window.alert(\'Hello from Blockly!\');', code.trim(), 'equal');
   });
 });