@testable import PureYAML
import Testing

@Suite("Value Hashing")
struct ValueHashableTests {
    typealias Value = PureYAML.Model.Value

    @Test("NaN double values compare equal to themselves")
    func test_doubleNaNValuesAreEqual() {
        #expect(Value.double(.nan) == Value.double(.nan))
        #expect(Value.double(.nan) != Value.double(1.0))
        #expect(Value.double(1.0) == Value.double(1.0))
    }

    @Test("Value hashing is consistent with equality, including NaN")
    func test_valueHashingIsConsistentWithEqualityIncludingNaN() {
        // Two equal NaN values must collapse to one Set element, which only
        // holds if hash(into:) agrees with the custom == for NaN.
        let set: Set<Value> = [.double(.nan), .double(.nan)]
        #expect(set.count == 1)

        // Distinct values stay distinct as dictionary keys.
        let table: [Value: Int] = [
            .double(.nan): 1,
            .int(1): 2,
            .string("1"): 3,
            .bool(true): 4,
            .null: 5,
        ]
        #expect(table.count == 5)
        #expect(table[.double(.nan)] == 1)
        #expect(table[.int(1)] == 2)
    }

    @Test("Equal values across cases hash and compare distinctly")
    func test_distinctCasesAreNotEqual() {
        #expect(Value.int(1) != Value.string("1"))
        #expect(Value.int(1) != Value.double(1.0))
        #expect(Value.bool(true) != Value.int(1))
        #expect(Value.null != Value.string("null"))
        let set: Set<Value> = [.int(1), .string("1"), .double(1.0), .bool(true), .null]
        #expect(set.count == 5)
    }
}