Fall back to en strings (fixes #738)

test/index.html

@@ -144,6 +144,7 @@
 
     <!-- include spec files here... -->
     <script src="spec/lib/d3.keybinding.js"></script>
+    <script src="spec/lib/locale.js"></script>
 
     <script src="spec/actions/add_midpoint.js"></script>
     <script src="spec/actions/add_entity.js"></script>

test/index_packaged.html

@@ -22,6 +22,7 @@
 
     <!-- include spec files here... -->
     <script src="spec/lib/d3.keybinding.js"></script>
+    <script src="spec/lib/locale.js"></script>
 
     <script src="spec/actions/add_midpoint.js"></script>
     <script src="spec/actions/add_entity.js"></script>

test/spec/lib/locale.js

@@ -0,0 +1,26 @@
+describe("locale", function() {
+    var saved, error;
+
+    beforeEach(function() {
+        saved = locale;
+        error = console.error;
+        console.error = function () {};
+        locale = { _current: 'en', en: {test: 'test', foo: 'bar'}, __: {}}
+    });
+
+    afterEach(function() {
+        locale = saved;
+        console.error = error;
+    });
+
+    describe("t", function() {
+        it("defaults to locale._current", function() {
+            expect(t('test')).to.equal('test');
+        });
+
+        it("falls back to en", function() {
+            locale._current = '__';
+            expect(t('test')).to.equal('test');
+        });
+    });
+});