tests: add 'fails on non-Linux system'

test/exec.bats

@@ -140,3 +140,21 @@ $envvarname=/unusual/shim/location:/another/shim/location
 _PYENV_SHIM_PATH=
 !
 }
+
+@test "fails on non-Linux system" {
+  # Make sure to use the system version of Python
+  mkdir -p "$PYENV_TEST_DIR"
+  cd "$PYENV_TEST_DIR"
+  echo '' > .python-version
+
+  run uname -s
+  if [ "$output" != Linux ]; then
+    run pyenv-exec -N env
+    assert_failure
+    assert_output 'Error: the --environment option is supported only on Linux'
+  else
+    run pyenv-exec -N env
+    echo "$status"
+    assert_success
+  fi
+}