Use correct locale, fall back to en if we don't have translations

FREEBIE

test/i18n_test.js

@@ -0,0 +1,25 @@
+describe('i18n', function() {
+  describe('i18n', function() {
+    it('returns undefined for unknown string', function() {
+      assert.strictEqual(i18n('random'), undefined);
+    });
+    it('returns message for given string', function() {
+      assert.equal(i18n('reportIssue'), 'Report an issue');
+    });
+    it('returns message with single substitution', function() {
+      const actual = i18n('attemptingReconnection', 5);
+      assert.equal(actual, 'Attempting reconnect in 5 seconds')
+    });
+    it('returns message with multiple substitutions', function() {
+      const actual = i18n('verifyContact', ['<strong>', '</strong>']);
+      assert.equal(actual, 'You may wish to <strong> verify </strong> your safety number with this contact.');
+    });
+  });
+
+  describe('getLocale', function() {
+    it('returns a string with length two or greater', function() {
+      const locale = i18n.getLocale();
+      assert.isAtLeast(locale.trim().length, 2);
+    });
+  });
+});