diff --git a/core/input.js b/core/input.js
index ddfa1d772..3da031451 100644
--- a/core/input.js
+++ b/core/input.js
@@ -106,8 +106,9 @@ Blockly.Input.prototype.insertFieldAt = function(index, field, opt_name) {
     throw Error('index ' + index + ' out of bounds.');
   }
 
-  // Empty string, Null or undefined generates no field, unless field is named.
-  if (!field && !opt_name) {
+  // Falsy field values don't generate a field, unless the field is an empty
+  // string and named.
+  if (!field && !(field == '' && opt_name)) {
     return index;
   }
   // Generate a FieldLabel when given a plain text field.
diff --git a/tests/jsunit/index.html b/tests/jsunit/index.html
index 2f037075c..7510fd7eb 100644
--- a/tests/jsunit/index.html
+++ b/tests/jsunit/index.html
@@ -24,7 +24,6 @@
     <script src="extensions_test.js"></script>
     <script src="generator_test.js"></script>
     <script src="gesture_test.js"></script>
-    <script src="input_test.js"></script>
     <script src="json_test.js"></script>
     <script src="metrics_test.js"></script>
     <script src="names_test.js"></script>
diff --git a/tests/jsunit/input_test.js b/tests/jsunit/input_test.js
deleted file mode 100644
index 35bdd4f30..000000000
--- a/tests/jsunit/input_test.js
+++ /dev/null
@@ -1,202 +0,0 @@
-/**
- * @license
- * Visual Blocks Editor
- *
- * Copyright 2017 Google Inc.
- * https://developers.google.com/blockly/
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *   http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
- /**
-  * @fileoverview Tests for Blockly.Input
-  */
-'use strict';
-
-function test_appendField_simple() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var field1 = new Blockly.FieldLabel('#1');
-  var field2 = new Blockly.FieldLabel('#2');
-
-  // Preconditions
-  assertEquals(0, input.fieldRow.length);
-
-  // Actual Tests
-  input.appendField(field1, 'first');
-  assertEquals(1, input.fieldRow.length);
-  assertEquals(field1, input.fieldRow[0]);
-  assertEquals('first', input.fieldRow[0].name);
-  assertEquals(block, field1.sourceBlock_);
-
-  input.appendField(field2, 'second');
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(field2, input.fieldRow[1]);
-  assertEquals('second', input.fieldRow[1].name);
-  assertEquals(block, field2.sourceBlock_);
-}
-
-function test_appendField_string() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var labelText = 'label';
-
-  // Preconditions
-  assertEquals(0, input.fieldRow.length);
-
-  // Actual Tests
-  input.appendField(labelText, 'name');
-  assertEquals(1, input.fieldRow.length);
-  assertEquals(Blockly.FieldLabel, input.fieldRow[0].constructor);
-  assertEquals(labelText, input.fieldRow[0].getValue());
-  assertEquals('name', input.fieldRow[0].name);
-}
-
-function test_appendField_prefix() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var prefix = new Blockly.FieldLabel('prefix');
-  var field = new Blockly.FieldLabel('field');
-  field.prefixField = prefix;
-
-  // Preconditions
-  assertEquals(0, input.fieldRow.length);
-
-  // Actual Tests
-  input.appendField(field);
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(prefix, input.fieldRow[0]);
-  assertEquals(field, input.fieldRow[1]);
-}
-
-function test_appendField_suffix() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var suffix = new Blockly.FieldLabel('suffix');
-  var field = new Blockly.FieldLabel('field');
-  field.suffixField = suffix;
-
-  // Preconditions
-  assertEquals(0, input.fieldRow.length);
-
-  // Actual Tests
-  input.appendField(field);
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(field, input.fieldRow[0]);
-  assertEquals(suffix, input.fieldRow[1]);
-}
-
-function test_insertFieldAt_simple() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var before = new Blockly.FieldLabel('before');
-  var after = new Blockly.FieldLabel('after');
-  var between = new Blockly.FieldLabel('between');
-  input.appendField(before);
-  input.appendField(after);
-
-  // Preconditions
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(after, input.fieldRow[1]);
-
-  // Actual Tests
-  input.insertFieldAt(1, between, 'name');
-  assertEquals(3, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(between, input.fieldRow[1]);
-  assertEquals('name', input.fieldRow[1].name);
-  assertEquals(after, input.fieldRow[2]);
-}
-
-function test_insertFieldAt_string() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var before = new Blockly.FieldLabel('before');
-  var after = new Blockly.FieldLabel('after');
-  var labelText = 'label';
-  input.appendField(before);
-  input.appendField(after);
-
-  // Preconditions
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(after, input.fieldRow[1]);
-
-  // Actual Tests
-  input.insertFieldAt(1, labelText, 'name');
-  assertEquals(3, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(Blockly.FieldLabel, input.fieldRow[1].constructor);
-  assertEquals(labelText, input.fieldRow[1].getValue());
-  assertEquals('name', input.fieldRow[1].name);
-  assertEquals(after, input.fieldRow[2]);
-}
-
-function test_insertFieldAt_prefix() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var before = new Blockly.FieldLabel('before');
-  var after = new Blockly.FieldLabel('after');
-  var prefix = new Blockly.FieldLabel('prefix');
-  var between = new Blockly.FieldLabel('between');
-  between.prefixField = prefix;
-  input.appendField(before);
-  input.appendField(after);
-
-  // Preconditions
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(after, input.fieldRow[1]);
-
-  // Actual Tests
-  input.insertFieldAt(1, between);
-  assertEquals(4, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(prefix, input.fieldRow[1]);
-  assertEquals(between, input.fieldRow[2]);
-  assertEquals(after, input.fieldRow[3]);
-}
-
-function test_insertFieldAt_suffix() {
-  var ws = new Blockly.Workspace();
-  var block = new Blockly.Block(ws);
-  var input = new Blockly.Input(Blockly.DUMMY_INPUT, 'INPUT', block);
-  var before = new Blockly.FieldLabel('before');
-  var after = new Blockly.FieldLabel('after');
-  var suffix = new Blockly.FieldLabel('suffix');
-  var between = new Blockly.FieldLabel('between');
-  between.suffixField = suffix;
-  input.appendField(before);
-  input.appendField(after);
-
-  // Preconditions
-  assertEquals(2, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(after, input.fieldRow[1]);
-
-  // Actual Tests
-  input.insertFieldAt(1, between);
-  assertEquals(4, input.fieldRow.length);
-  assertEquals(before, input.fieldRow[0]);
-  assertEquals(between, input.fieldRow[1]);
-  assertEquals(suffix, input.fieldRow[2]);
-  assertEquals(after, input.fieldRow[3]);
-}
diff --git a/tests/mocha/index.html b/tests/mocha/index.html
index 862398539..49339b471 100644
--- a/tests/mocha/index.html
+++ b/tests/mocha/index.html
@@ -45,6 +45,7 @@
     <script src="field_textinput_test.js"></script>
     <script src="field_variable_test.js"></script>
     <script src="gesture_test.js"></script>
+    <script src="input_test.js"></script>
     <script src="key_map_test.js"></script>
     <script src="metrics_test.js"></script>
     <script src="names_test.js"></script>
diff --git a/tests/mocha/input_test.js b/tests/mocha/input_test.js
new file mode 100644
index 000000000..b4f95f8b6
--- /dev/null
+++ b/tests/mocha/input_test.js
@@ -0,0 +1,311 @@
+/**
+ * @license
+ * Visual Blocks Editor
+ *
+ * Copyright 2019 Google Inc.
+ * https://developers.google.com/blockly/
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+suite('Inputs', function() {
+  setup(function() {
+    Blockly.defineBlocksWithJsonArray([
+      {
+        "type": "empty_block",
+        "message0": "",
+        "args0": []
+      },
+    ]);
+
+    this.workspace = Blockly.inject('blocklyDiv');
+    this.block = Blockly.Xml.domToBlock(Blockly.Xml.textToDom(
+        '<block type="empty_block"/>'
+    ), this.workspace);
+
+    this.renderStub = sinon.stub(this.block, 'render');
+    this.bumpNeighboursStub = sinon.stub(this.block, 'bumpNeighbours_');
+
+    this.dummy = this.block.appendDummyInput('DUMMY');
+    this.value = this.block.appendValueInput('VALUE');
+    this.statement = this.block.appendStatementInput('STATEMENT');
+
+    this.renderStub.resetHistory();
+    this.bumpNeighboursStub.resetHistory();
+  });
+  teardown(function() {
+    this.renderStub.restore();
+    this.bumpNeighboursStub.restore();
+
+    delete Blockly.Blocks['empty_block'];
+    this.workspace.dispose();
+  });
+  suite('Insert Field At', function() {
+    suite('Index Bounds', function() {
+      test('< 0', function() {
+        var field = new Blockly.FieldLabel('field');
+        chai.assert.throws(function() {
+          this.dummy.insertFieldAt(-1, field);
+        });
+      });
+      test('> length', function() {
+        var field = new Blockly.FieldLabel('field');
+        chai.assert.throws(function() {
+          this.dummy.insertFieldAt(1, field);
+        });
+      });
+    });
+    suite('Values', function() {
+      // We're mostly just testing that it doesn't throw errors.
+      test('Field', function() {
+        var field = new Blockly.FieldLabel('field');
+        this.dummy.insertFieldAt(0, field);
+        chai.assert.equal(this.dummy.fieldRow[0], field);
+      });
+      test('String', function() {
+        this.dummy.insertFieldAt(0, 'field');
+        chai.assert.instanceOf(this.dummy.fieldRow[0], Blockly.FieldLabel);
+      });
+      test('Empty String', function() {
+        this.dummy.insertFieldAt(0, '');
+        chai.assert.isEmpty(this.dummy.fieldRow);
+      });
+      test('Empty String W/ Name', function() {
+        this.dummy.insertFieldAt(0, '', 'NAME');
+        chai.assert.instanceOf(this.dummy.fieldRow[0], Blockly.FieldLabel);
+      });
+      test('Null', function() {
+        this.dummy.insertFieldAt(0, null);
+        chai.assert.isEmpty(this.dummy.fieldRow);
+      });
+      test('Undefined', function() {
+        this.dummy.insertFieldAt(0, undefined);
+        chai.assert.isEmpty(this.dummy.fieldRow);
+      });
+    });
+    suite('Prefixes and Suffixes', function() {
+      test('Prefix', function() {
+        var field = new Blockly.FieldLabel('field');
+        var prefix = new Blockly.FieldLabel('prefix');
+        field.prefixField = prefix;
+
+        this.dummy.appendField(field);
+        chai.assert.deepEqual(this.dummy.fieldRow, [prefix, field]);
+      });
+      test('Suffix', function() {
+        var field = new Blockly.FieldLabel('field');
+        var suffix = new Blockly.FieldLabel('suffix');
+        field.suffixField = suffix;
+
+        this.dummy.appendField(field);
+        chai.assert.deepEqual(this.dummy.fieldRow, [field, suffix]);
+      });
+      test('Prefix and Suffix', function() {
+        var field = new Blockly.FieldLabel('field');
+        var prefix = new Blockly.FieldLabel('prefix');
+        var suffix = new Blockly.FieldLabel('suffix');
+        field.prefixField = prefix;
+        field.suffixField = suffix;
+
+        this.dummy.appendField(field);
+        chai.assert.deepEqual(this.dummy.fieldRow, [prefix, field, suffix]);
+      });
+      test('Dropdown - Prefix', function() {
+        var field = new Blockly.FieldDropdown(
+            [
+              ['prefix option1', 'OPTION1'],
+              ['prefix option2', 'OPTION2']
+            ]
+        );
+
+        this.dummy.appendField(field);
+        chai.assert.equal(this.dummy.fieldRow.length, 2);
+      });
+      test('Dropdown - Suffix', function() {
+        var field = new Blockly.FieldDropdown(
+            [
+              ['option1 suffix', 'OPTION1'],
+              ['option2 suffix', 'OPTION2']
+            ]
+        );
+
+        this.dummy.appendField(field);
+        chai.assert.equal(this.dummy.fieldRow.length, 2);
+      });
+      test('Dropdown - Prefix and Suffix', function() {
+        var field = new Blockly.FieldDropdown(
+            [
+              ['prefix option1 suffix', 'OPTION1'],
+              ['prefix option2 suffix', 'OPTION2']
+            ]
+        );
+
+        this.dummy.appendField(field);
+        chai.assert.equal(this.dummy.fieldRow.length, 3);
+      });
+    });
+    suite('Field Initialization', function() {
+      test('Rendered', function() {
+        var field = new Blockly.FieldLabel('field');
+        var setBlockSpy = sinon.spy(field, 'setSourceBlock');
+        var initSpy = sinon.spy(field, 'init');
+
+        this.dummy.insertFieldAt(0, field);
+        chai.assert(setBlockSpy.calledOnce);
+        chai.assert.equal(setBlockSpy.getCall(0).args[0], this.block);
+        chai.assert(initSpy.calledOnce);
+        console.log(this.renderStub.callCount);
+        chai.assert(this.renderStub.calledOnce);
+        chai.assert(this.bumpNeighboursStub.calledOnce);
+
+        setBlockSpy.restore();
+        initSpy.restore();
+      });
+      // TODO: InsertFieldAt does not properly handle initialization in
+      //  headless mode.
+      test.skip('Headless', function() {
+        var field = new Blockly.FieldLabel('field');
+        var setBlockSpy = sinon.spy(field, 'setSourceBlock');
+        var initModelSpy = sinon.spy(field, 'initModel');
+
+        this.block.rendered = false;
+
+        this.dummy.insertFieldAt(0, field);
+        chai.assert(setBlockSpy.calledOnce);
+        chai.assert.equal(setBlockSpy.getCall(0).args[0], this.block);
+        chai.assert(initModelSpy.calledOnce);
+        chai.assert(this.renderStub.notCalled);
+        chai.assert(this.bumpNeighboursStub.notCalled);
+
+        setBlockSpy.restore();
+        initModelSpy.restore();
+      });
+    });
+  });
+  suite('Remove Field', function() {
+    test('Field Not Found', function() {
+      chai.assert.throws(function() {
+        this.dummy.removeField('FIELD');
+      });
+    });
+    test('Rendered', function() {
+      var field = new Blockly.FieldLabel('field');
+      var disposeSpy = sinon.spy(field, 'dispose');
+      this.dummy.appendField(field, 'FIELD');
+
+      this.renderStub.resetHistory();
+      this.bumpNeighboursStub.resetHistory();
+
+      this.dummy.removeField('FIELD');
+      chai.assert(disposeSpy.calledOnce);
+      chai.assert(this.renderStub.calledOnce);
+      chai.assert(this.bumpNeighboursStub.calledOnce);
+    });
+    test('Headless', function() {
+      var field = new Blockly.FieldLabel('field');
+      var disposeSpy = sinon.spy(field, 'dispose');
+      this.dummy.appendField(field, 'FIELD');
+
+      this.renderStub.resetHistory();
+      this.bumpNeighboursStub.resetHistory();
+
+      this.block.rendered = false;
+
+      this.dummy.removeField('FIELD');
+      chai.assert(disposeSpy.calledOnce);
+      chai.assert(this.renderStub.notCalled);
+      chai.assert(this.bumpNeighboursStub.notCalled);
+    });
+  });
+  suite('Field Ordering/Manipulation', function() {
+    setup(function() {
+      this.a = new Blockly.FieldLabel('a');
+      this.b = new Blockly.FieldLabel('b');
+      this.c = new Blockly.FieldLabel('c');
+    });
+    test('Append A, B, C', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.appendField(this.c, 'C');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.a, this.b, this.c]);
+    });
+    test('Append B, C; Insert A at Start', function() {
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.appendField(this.c, 'C');
+      this.dummy.insertFieldAt(0, this.a, 'A');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.a, this.b, this.c]);
+    });
+    test('Append A, C; Insert B Between', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.c, 'C');
+      this.dummy.insertFieldAt(1, this.b, 'B');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.a, this.b, this.c]);
+    });
+    test('Append A, B; Insert C at End', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.insertFieldAt(2, this.c, 'C');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.a, this.b, this.c]);
+    });
+    test('Append A, B, C; Remove A, B, C', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.appendField(this.c, 'C');
+
+      this.dummy.removeField('A');
+      this.dummy.removeField('B');
+      this.dummy.removeField('C');
+
+      chai.assert.isEmpty(this.dummy.fieldRow);
+    });
+    test('Append A, B, C; Remove A', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.appendField(this.c, 'C');
+
+      this.dummy.removeField('A');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.b, this.c]);
+    });
+    test('Append A, B, C; Remove B', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.appendField(this.c, 'C');
+
+      this.dummy.removeField('B');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.a, this.c]);
+    });
+    test('Append A, B, C; Remove C', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.appendField(this.c, 'C');
+
+      this.dummy.removeField('C');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.a, this.b]);
+    });
+    test('Append A, B; Remove A; Append C', function() {
+      this.dummy.appendField(this.a, 'A');
+      this.dummy.appendField(this.b, 'B');
+      this.dummy.removeField('A');
+      this.dummy.appendField(this.c, 'C');
+
+      chai.assert.deepEqual(this.dummy.fieldRow, [this.b, this.c]);
+    });
+  });
+});