Add unit test for system locale with thousands separator comma
Install en_US.UTF-8 locale in Dockerfile
diff --git a/build/docker/ubuntu-bionic/Dockerfile b/build/docker/ubuntu-bionic/Dockerfile
index 291aa5d..0407a6f 100644
--- a/build/docker/ubuntu-bionic/Dockerfile
+++ b/build/docker/ubuntu-bionic/Dockerfile
@@ -253,6 +253,13 @@
rm swift-5.1.4-RELEASE-ubuntu18.04.tar.gz && \
swift --version
+# Locale(s) for cpp unit tests
+RUN apt-get install -y --no-install-recommends \
+`# Locale dependencies` \
+ locales && \
+ locale-gen en_US.UTF-8 && \
+ update-locale
+
# cppcheck-1.82 has a nasty cpp parser bug, so we're using something newer
RUN apt-get install -y --no-install-recommends \
`# Static Code Analysis dependencies` \