Regex with "|" doesn't work

[nishantwrp]

Doing fuzztest::InRegexp(R"(a)|(b)") gives the error

Failed precondition (re != nullptr): Invalid RE2 regular expression.

Is that by design because I am able to do OneOf(InRegexp(R"(a)"), InRegexp(R"(b)")) without any errors

[nishantwrp]

From fuzztest docs

You can also use regular expressions to define a string domain. The InRegexp domain represents strings that are sentences of a given regular expression. You can use any regular expression syntax accepted by RE2. For example:

From re2 docs

Two regular expressions can be alternated or concatenated to form a new regular expression: if e1 matches s and e2 matches t, then e1|e2 matches s or t, and e1e2 matches st.