data class UnresolvedReference(val reference: Expr) : ErrorReason
    data class NonReadableProperty(val property: DataProperty) : ErrorReason
    data class ReadOnlyPropertyAssignment(val property: DataProperty) : ErrorReason
    data class UnresolvedFunctionCallArguments(val functionCall: FunctionCall) : ErrorReason
    data class UnresolvedFunctionCallReceiver(val functionCall: FunctionCall) : ErrorReason

            is ErrorReason.UnresolvedReference -> UnresolvedName
            is ErrorReason.AssignmentTypeMismatch -> ValueTypeMismatch
            is ErrorReason.ReadOnlyPropertyAssignment -> NotAssignable
            ErrorReason.UnresolvedAssignmentRhs -> UnresolvedValueUsed

            ErrorReason.MissingConfigureLambda,
            ErrorReason.UnusedConfigureLambda,

object PropertyTest {
    @Test
    fun `read-only property cannot be written`() {
        val result = schema().resolve("x = y")
        val singleError = result.errors.single().errorReason
        assertIs<ErrorReason.ReadOnlyPropertyAssignment>(singleError)
        assertEquals("x", singleError.property.name)
    }

    @Test
    fun `write-only property cannot be read`() {
        val result = schema().resolve("y = z")

            null
        } else {
            var hasErrors = false
            if (lhsResolution.property.isReadOnly) {
                errorCollector.collect(ResolutionError(assignment, ErrorReason.ReadOnlyPropertyAssignment(lhsResolution.property)))
                hasErrors = true
            }
            val rhsResolution = expressionResolver.doResolveExpression(this, assignment.rhs)
            if (rhsResolution == null) {

        is ErrorReason.ExternalReassignment -> "assignment to external property"
        ErrorReason.MissingConfigureLambda -> "a configuring block expected but not found"
        is ErrorReason.ReadOnlyPropertyAssignment -> "assignment to read-only property '${errorReason.property.name}"
        ErrorReason.UnitAssignment -> "assignment of a Unit value"
        ErrorReason.UnresolvedAssignmentLhs -> "unresolved assignment target"