bstr_test.dart

@TestOn('windows')

import 'dart:ffi';

import 'package:ffi/ffi.dart';
import 'package:test/test.dart';
import 'package:win32/win32.dart';

const TEST_RUNS = 500;

void main() {
  test('BSTR allocation', () {
    const testString = 'Hello world';
    final bstr = BSTR.fromString(testString);

    // A BSTR should have a DWORD-length prefix containing its length.
    final pIndex =
        Pointer<DWORD>.fromAddress(bstr.ptr.address - sizeOf<DWORD>());
    expect(pIndex.value, equals(testString.length * 2));

    expect(bstr.ptr.toDartString(), equals(testString));

    // A BSTR should end with a word-length null terminator.
    final pNull =
        Pointer<DWORD>.fromAddress(bstr.ptr.address + testString.length * 2);
    expect(pNull.value, isZero);
    bstr.free();
  });

  test('Long BSTRs', () {
    // This string is 4MB (32 chars * 2 bytes * 65536)
    final longString = 'A very long string with padding.' * 65536;
    final bstr = BSTR.fromString(longString);

    // A BSTR should have a DWORD-length prefix containing its length.
    final pIndex =
        Pointer<DWORD>.fromAddress(bstr.ptr.address - sizeOf<DWORD>());
    expect(pIndex.value, equals(longString.length * 2));

    expect(bstr.ptr.toDartString(), equals(longString));

    // A BSTR should end with a word-length null terminator.
    final pNull =
        Pointer<DWORD>.fromAddress(bstr.ptr.address + longString.length * 2);
    expect(pNull.value, isZero);
    bstr.free();
  });

  test('BSTR lengths', () {
    const testString = 'Longhorn is a bar in the village resort between the '
        'Whistler and Blackcomb mountains';
    final bstr = BSTR.fromString(testString);

    expect(testString.length, equals(84));
    expect(bstr.byteLength, equals(84 * 2));
    expect(bstr.length, equals(84));

    expect(bstr.toString(), equals(testString));

    bstr.free();
  });

  test('BSTR clone', () {
    const testString = 'This message is not unique.';
    final original = BSTR.fromString(testString);
    final clone = original.clone();

    // Text should be equal, but pointer address should not be equal
    expect(original.ptr.toDartString(), equals(clone.ptr.toDartString()));
    expect(original.toString(), equals(clone.toString()));
    expect(original.ptr, isNot(equals(clone.ptr)));

    clone.free();
    original.free();
  });

  test('BSTR concatenation', () {
    final first = BSTR.fromString('Windows');
    final second = BSTR.fromString(' and Dart');
    final matchInHeaven = first + second;

    expect(matchInHeaven.toString(), equals('Windows and Dart'));

    [first, second, matchInHeaven].map((object) => object.free());
  });
}