diff --git a/test/unit/extension_text_to_speech.js b/test/unit/extension_text_to_speech.js
new file mode 100644
index 00000000..64061844
--- /dev/null
+++ b/test/unit/extension_text_to_speech.js
@@ -0,0 +1,30 @@
+const test = require('tap').test;
+const TextToSpeech = require('../../src/extensions/scratch3_text2speech/index.js');
+
+const fakeStage = {
+    textToSpeechLanguage: null
+};
+
+const fakeRuntime = {
+    getTargetForStage: () => fakeStage,
+    on: () => {} // Stub out listener methods used in constructor.
+};
+
+const ext = new TextToSpeech(fakeRuntime);
+
+test('if no language is saved in the project, use default', t => {
+    t.strictEqual(ext.getCurrentLanguage(), 'en');
+    t.end();
+});
+
+test('if an unsupported language is dropped onto the set language block, use default', t => {
+    ext.setLanguage({LANGUAGE: 'nope'});
+    t.strictEqual(ext.getCurrentLanguage(), 'en');
+    t.end();
+});
+
+test('get the extension locale for a supported locale that differs', t => {
+    ext.setCurrentLanguage('ja-Hira');
+    t.strictEqual(ext.getCurrentLanguage(), 'ja');
+    t.end();
+});