Macro optional 

macro_rules! optional {
    ($inner:expr) => { ... };
}

Matches a JSON field that may be absent, null, or satisfy an inner matcher.

Examples

let value = j!({ "id": 42 });
assert_that!(
    value,
    json::pat!({
        "id": eq(42),
        "nickname": json::optional!("Bob"),
        "alt": json::optional!(j!("Robert")),
        "tag": json::optional!(starts_with("B"))
    })
);

Supported Inputs

• Literal JSON-compatible values
• Direct serde_json::Value
• Native googletest matchers