Add nvm_clang_version to ensure clang version > 3.5

test/fast/Unit tests/nvm_clang_version

@@ -0,0 +1,62 @@
+#!/bin/sh
+
+cleanup () {
+  unset -f die
+}
+
+die () { echo -e "$@" ; cleanup ;  exit 1; }
+
+if type "clang" > /dev/null 2>&1 ; then
+  clang_exec="$(type "clang")"
+  sudo rm -rf "${clang_exec}"
+fi
+if type "clang++" > /dev/null 2>&1 ; then
+  clangxx_exec="$(type "clang++")"
+  sudo rm -rf "${clangxx_exec}"
+fi
+
+NVM_ENV=testing \. ../../../nvm.sh
+
+clang() {
+  if [ "$1" = "--version" ]; then
+    echo "${VERSION_MESSAGE}"
+  fi
+}
+
+assert_version_is() {
+  if [ "${1}" != "${2}" ]; then
+    die "Expected ${2}, got ${1}, origin version message:\n${VERSION_MESSAGE}"
+    return 1
+  fi
+}
+
+CLANG_VERSION_ON_DEBIAN_JESSIE="Debian clang version 3.5.0-10 (tags/RELEASE_350/final) (based on LLVM 3.5.0)
+Target: x86_64-pc-linux-gnu
+Thread model: posix"
+
+CLANG_VERSION_ON_UBUNTU_TRUSTY="Ubuntu clang version 3.4-1ubuntu3 (tags/RELEASE_34/final) (based on LLVM 3.4)
+Target: x86_64-pc-linux-gnu
+Thread model: posix"
+
+CLANG_VERSION_ON_ARCHLINUX="clang version 3.9.0 (tags/RELEASE_390/final)
+Target: x86_64-unknown-linux-gnu
+Thread model: posix
+InstalledDir: /usr/sbin"
+
+CLANG_VERSION_ON_FREEBSD="FreeBSD clang version 3.4.1 (tags/RELEASE_34/dot1-final 208032) 20140512
+Target: x86_64-unknown-freebsd10.3
+Thread model: posix"
+
+VERSION_MESSAGE="${CLANG_VERSION_ON_DEBIAN_JESSIE}"
+assert_version_is "$(nvm_clang_version)" "3.5.0"
+
+VERSION_MESSAGE="${CLANG_VERSION_ON_UBUNTU_TRUSTY}"
+assert_version_is "$(nvm_clang_version)" "3.4"
+
+VERSION_MESSAGE="${CLANG_VERSION_ON_ARCHLINUX}"
+assert_version_is "$(nvm_clang_version)" "3.9.0"
+
+VERSION_MESSAGE="${CLANG_VERSION_ON_FREEBSD}"
+assert_version_is "$(nvm_clang_version)" "3.4.1"
+
+cleanup