+ {
+ echo "ERROR: Invalid \`BT_TESTS_BUILDDIR\` variable (\`\$BT_TESTS_BUILDDIR/Makefile\`"
+ echo "doesn't exist)."
+ echo ""
+ echo "If you build out of tree, export and set the \`BT_TESTS_BUILDDIR\` environment"
+ echo "variable to the built \`tests\` directory."
+ } >&2