diff --git a/tests/mocha/field_dropdown_test.js b/tests/mocha/field_dropdown_test.js
index de5571a2e..3bd374141 100644
--- a/tests/mocha/field_dropdown_test.js
+++ b/tests/mocha/field_dropdown_test.js
@@ -33,7 +33,7 @@ suite('Dropdown Fields', function() {
       chai.assert.throws(function() {
         new Blockly.FieldDropdown([1, 2, 3]);
       });
-      chai.assert(stub.calledThrice);
+      sinon.assert.calledThrice(stub);
       stub.restore();
     });
     test('Array Items with Invalid IDs', function() {
@@ -41,7 +41,7 @@ suite('Dropdown Fields', function() {
       chai.assert.throws(function() {
         new Blockly.FieldDropdown([['1', 1], ['2', 2], ['3', 3]]);
       });
-      chai.assert(stub.calledThrice);
+      sinon.assert.calledThrice(stub);
       stub.restore();
     });
     test('Array Items with Invalid Content', function() {
@@ -49,7 +49,7 @@ suite('Dropdown Fields', function() {
       chai.assert.throws(function() {
         new Blockly.FieldDropdown([[1, '1'], [2, '2'], [3, '3']]);
       });
-      chai.assert(stub.calledThrice);
+      sinon.assert.calledThrice(stub);
       stub.restore();
     });
     test('Text Dropdown', function() {
@@ -99,7 +99,7 @@ suite('Dropdown Fields', function() {
       chai.assert.throws(function() {
         Blockly.FieldDropdown.fromJson({ options: [1, 2, 3] });
       });
-      chai.assert(stub.calledThrice);
+      sinon.assert.calledThrice(stub);
       stub.restore();
     });
     test('Array Items with Invalid IDs', function() {
@@ -108,7 +108,7 @@ suite('Dropdown Fields', function() {
         Blockly.FieldDropdown.fromJson(
             { options:[['1', 1], ['2', 2], ['3', 3]] });
       });
-      chai.assert(stub.calledThrice);
+      sinon.assert.calledThrice(stub);
       stub.restore();
     });
     test('Array Items with Invalid Content', function() {
@@ -117,7 +117,7 @@ suite('Dropdown Fields', function() {
         Blockly.FieldDropdown.fromJson(
             { options:[[1, '1'], [2, '2'], [3, '3']] });
       });
-      chai.assert(stub.calledThrice);
+      sinon.assert.calledThrice(stub);
       stub.restore();
     });
     test('Text Dropdown', function() {
diff --git a/tests/mocha/field_variable_test.js b/tests/mocha/field_variable_test.js
index a97cd73b2..c266bbf30 100644
--- a/tests/mocha/field_variable_test.js
+++ b/tests/mocha/field_variable_test.js
@@ -125,7 +125,7 @@ suite('Variable Fields', function() {
       var stub = sinon.stub(console, 'warn');
       variableField.setValue(undefined);
       assertValue(variableField, 'name1');
-      chai.assert(stub.calledOnce);
+      sinon.assert.calledOnce(stub);
       stub.restore();
     });
     test('New Variable ID', function() {
@@ -147,7 +147,7 @@ suite('Variable Fields', function() {
       var stub = sinon.stub(console, 'warn');
       variableField.setValue('id1');
       assertValue(variableField, 'name1');
-      chai.assert(stub.calledOnce);
+      sinon.assert.calledOnce(stub);
       stub.restore();
     });
   });
diff --git a/tests/mocha/input_test.js b/tests/mocha/input_test.js
index 35b4de2b9..ba0206cef 100644
--- a/tests/mocha/input_test.js
+++ b/tests/mocha/input_test.js
@@ -145,11 +145,11 @@ suite('Inputs', function() {
         var initSpy = sinon.spy(field, 'init');
 
         this.dummy.insertFieldAt(0, field);
-        chai.assert(setBlockSpy.calledOnce);
+        sinon.assert.calledOnce(setBlockSpy);
         chai.assert.equal(setBlockSpy.getCall(0).args[0], this.block);
-        chai.assert(initSpy.calledOnce);
-        chai.assert(this.renderStub.calledOnce);
-        chai.assert(this.bumpNeighboursStub.calledOnce);
+        sinon.assert.calledOnce(initSpy);
+        sinon.assert.calledOnce(this.renderStub);
+        sinon.assert.calledOnce(this.bumpNeighboursStub);
 
         setBlockSpy.restore();
         initSpy.restore();
@@ -164,11 +164,11 @@ suite('Inputs', function() {
         this.block.rendered = false;
 
         this.dummy.insertFieldAt(0, field);
-        chai.assert(setBlockSpy.calledOnce);
+        sinon.assert.calledOnce(setBlockSpy);
         chai.assert.equal(setBlockSpy.getCall(0).args[0], this.block);
-        chai.assert(initModelSpy.calledOnce);
-        chai.assert(this.renderStub.notCalled);
-        chai.assert(this.bumpNeighboursStub.notCalled);
+        sinon.assert.calledOnce(initModelSpy);
+        sinon.assert.notCalled(this.renderStub);
+        sinon.assert.notCalled(this.bumpNeighboursStub);
 
         setBlockSpy.restore();
         initModelSpy.restore();
@@ -190,9 +190,9 @@ suite('Inputs', function() {
       this.bumpNeighboursStub.resetHistory();
 
       this.dummy.removeField('FIELD');
-      chai.assert(disposeSpy.calledOnce);
-      chai.assert(this.renderStub.calledOnce);
-      chai.assert(this.bumpNeighboursStub.calledOnce);
+      sinon.assert.calledOnce(disposeSpy);
+      sinon.assert.calledOnce(this.renderStub);
+      sinon.assert.calledOnce(this.bumpNeighboursStub);
     });
     test('Headless', function() {
       var field = new Blockly.FieldLabel('field');
@@ -205,9 +205,9 @@ suite('Inputs', function() {
       this.block.rendered = false;
 
       this.dummy.removeField('FIELD');
-      chai.assert(disposeSpy.calledOnce);
-      chai.assert(this.renderStub.notCalled);
-      chai.assert(this.bumpNeighboursStub.notCalled);
+      sinon.assert.calledOnce(disposeSpy);
+      sinon.assert.notCalled(this.renderStub);
+      sinon.assert.notCalled(this.bumpNeighboursStub);
     });
   });
   suite('Field Ordering/Manipulation', function() {
diff --git a/tests/mocha/navigation_test.js b/tests/mocha/navigation_test.js
index 555520340..7d6fccd0f 100644
--- a/tests/mocha/navigation_test.js
+++ b/tests/mocha/navigation_test.js
@@ -272,7 +272,7 @@ suite('Navigation', function() {
       sinon.spy(this.workspace.getCursor(), 'prev');
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.W;
       chai.assert.isTrue(Blockly.navigation.onKeyPress(this.mockEvent));
-      chai.assert.isTrue(this.workspace.getCursor().prev.calledOnce);
+      sinon.assert.calledOnce(this.workspace.getCursor().prev);
       chai.assert.equal(Blockly.navigation.currentState_,
           Blockly.navigation.STATE_WS);
       this.workspace.getCursor().prev.restore();
@@ -283,7 +283,7 @@ suite('Navigation', function() {
       sinon.spy(cursor, 'next');
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.S;
       chai.assert.isTrue(Blockly.navigation.onKeyPress(this.mockEvent));
-      chai.assert.isTrue(cursor.next.calledOnce);
+      sinon.assert.calledOnce(cursor.next);
       chai.assert.equal(Blockly.navigation.currentState_,
           Blockly.navigation.STATE_WS);
       cursor.next.restore();
@@ -294,7 +294,7 @@ suite('Navigation', function() {
       sinon.spy(cursor, 'out');
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.A;
       chai.assert.isTrue(Blockly.navigation.onKeyPress(this.mockEvent));
-      chai.assert.isTrue(cursor.out.calledOnce);
+      sinon.assert.calledOnce(cursor.out);
       chai.assert.equal(Blockly.navigation.currentState_,
           Blockly.navigation.STATE_WS);
       cursor.out.restore();
@@ -305,7 +305,7 @@ suite('Navigation', function() {
       sinon.spy(cursor, 'in');
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.D;
       chai.assert.isTrue(Blockly.navigation.onKeyPress(this.mockEvent));
-      chai.assert.isTrue(cursor.in.calledOnce);
+      sinon.assert.calledOnce(cursor.in);
       chai.assert.equal(Blockly.navigation.currentState_,
           Blockly.navigation.STATE_WS);
       cursor.in.restore();
@@ -315,7 +315,7 @@ suite('Navigation', function() {
       sinon.spy(Blockly.navigation, 'modify_');
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.I;
       chai.assert.isTrue(Blockly.navigation.onKeyPress(this.mockEvent));
-      chai.assert.isTrue(Blockly.navigation.modify_.calledOnce);
+      sinon.assert.calledOnce(Blockly.navigation.modify_);
       chai.assert.equal(Blockly.navigation.currentState_,
           Blockly.navigation.STATE_WS);
       Blockly.navigation.modify_.restore();
@@ -386,7 +386,7 @@ suite('Navigation', function() {
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.N;
       var isHandled = Blockly.navigation.onKeyPress(this.mockEvent);
       chai.assert.isFalse(isHandled);
-      chai.assert.isFalse(field.onBlocklyAction.calledOnce);
+      sinon.assert.notCalled(field.onBlocklyAction);
 
       field.onBlocklyAction.restore();
     });
@@ -400,7 +400,7 @@ suite('Navigation', function() {
 
       var isHandled = Blockly.navigation.onBlocklyAction(Blockly.navigation.ACTION_OUT);
       chai.assert.isTrue(isHandled);
-      chai.assert.isTrue(field.onBlocklyAction.calledOnce);
+      sinon.assert.calledOnce(field.onBlocklyAction);
 
       field.onBlocklyAction.restore();
     });
@@ -414,7 +414,7 @@ suite('Navigation', function() {
       this.mockEvent.keyCode = Blockly.utils.KeyCodes.A;
       var isHandled = Blockly.navigation.onBlocklyAction(Blockly.navigation.ACTION_OUT);
       chai.assert.isTrue(isHandled);
-      chai.assert.isTrue(field.onBlocklyAction.calledOnce);
+      sinon.assert.calledOnce(field.onBlocklyAction);
 
       field.onBlocklyAction.restore();
     });
@@ -426,7 +426,7 @@ suite('Navigation', function() {
 
       var isHandled = Blockly.navigation.onKeyPress(this.mockEvent);
       chai.assert.isTrue(isHandled);
-      chai.assert.isTrue(Blockly.navigation.onBlocklyAction.calledOnce);
+      sinon.assert.calledOnce(Blockly.navigation.onBlocklyAction);
       chai.assert.isFalse(Blockly.getMainWorkspace().keyboardAccessibilityMode);
       Blockly.navigation.onBlocklyAction.restore();
     });
@@ -438,7 +438,7 @@ suite('Navigation', function() {
 
       var isHandled = Blockly.navigation.onKeyPress(this.mockEvent);
       chai.assert.isTrue(isHandled);
-      chai.assert.isTrue(Blockly.navigation.focusWorkspace_.calledOnce);
+      sinon.assert.calledOnce(Blockly.navigation.focusWorkspace_);
       chai.assert.isTrue(Blockly.getMainWorkspace().keyboardAccessibilityMode);
       Blockly.navigation.focusWorkspace_.restore();
     });