@testable import PureYAML
import Testing

/// An explicit key (`?`) in a flow mapping may have no key node: `? : v`, a trailing `? }` or
/// `? ]` or `? ,`, all denote a null key. The parser emits an empty key rather than failing to
/// find a node before the value indicator or terminator.
@Suite("Flow explicit empty key")
struct FlowExplicitEmptyKeyTests {
    @Test("An explicit key with a value but no key node is a null key")
    func test_explicitEmptyKeyWithValue() throws {
        #expect(try PureYAML.parse("{ ? : v }") == .mapping(.init([
            .init(keyNode: .string(""), value: .string("v")),
        ])))
    }

    @Test("A trailing explicit key with no node maps a null key to null")
    func test_trailingExplicitEmptyKey() throws {
        #expect(try PureYAML.parse("{ a, ? }") == .mapping(.init([
            .init(key: "a", value: .null),
            .init(keyNode: .string(""), value: .null),
        ])))
    }

    @Test("Suite case DFF7: a flow mapping ending with an empty explicit key")
    func test_dff7() throws {
        let yaml = "{\n? explicit: entry,\nimplicit: entry,\n?\n}\n"
        #expect(try PureYAML.parse(yaml) == .mapping(.init([
            .init(key: "explicit", value: .string("entry")),
            .init(key: "implicit", value: .string("entry")),
            .init(keyNode: .string(""), value: .null),
        ])))
    }
}