fix(dotnet): lock the installed .NET version (#707)

* fix(dotnet): lock the installed dotnet version

* chore(tests): missing bracket

Author: JGAntunes

Dockerfile

@@ -412,9 +412,10 @@ RUN gimme | bash
 #
 ################################################################################
 WORKDIR /tmp
+ENV DOTNET_VERSION 6.0
 RUN wget https://dot.net/v1/dotnet-install.sh
 RUN chmod u+x /tmp/dotnet-install.sh
-RUN /tmp/dotnet-install.sh -c Current
+RUN /tmp/dotnet-install.sh -c ${DOTNET_VERSION}
 ENV PATH "$PATH:/opt/buildhome/.dotnet/tools"
 ENV PATH "$PATH:/opt/buildhome/.dotnet"
 ENV DOTNET_ROOT "/opt/buildhome/.dotnet"

tests/dotnet/base.bats

@@ -0,0 +1,11 @@
+#!/usr/bin/env bats
+
+load "../helpers.sh"
+
+load '../../node_modules/bats-support/load'
+load '../../node_modules/bats-assert/load'
+
+@test 'dotnet version 6.0 is installed and available at startup' {
+  run dotnet --version
+  assert_output --partial "6.0"
+}