test_cmp typo.err output.err
'
+cat > typo.err << EOF
+error: did you mean \`--ambiguous\` (with two dashes ?)
+EOF
+
+test_expect_success 'detect possible typos' '
+ test_must_fail test-parse-options -ambiguous > output 2> output.err &&
+ test ! -s output &&
+ test_cmp typo.err output.err
+'
+
cat > expect <<EOF
boolean: 0
integer: 0