可可触摸单元测试期间无效的图形上下文

Question

我有一个iOS应用程序，我正在为其创建单元测试。行使的许多方法都会创建一个UibezierPath的实例，并在视图的绘制方法中被调用。测试通过，但我看到了输出中这种错误的许多实例：

<Error>: CGContextDrawPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

我想这是由于这些方法在绘制方法之外被调用，但这就是单位测试的全部内容！尽管测试通过，而消息现在只是一个烦人，但日志也被它们混乱了。任何有意义的数据都会丢失。我可以创建图形上下文以供单元测试使用吗？还有其他方法可以摆脱消息吗？谢谢！

编辑：这是正在测试的方法

- (id)visitBBPathRect:(BBPathDataRect *)pathData
{
    const int kNumCorners = 4;
    CGPoint upperLeft = pathData.rect.origin;
    CGPoint upperRight = CGPointMake(
                                     CGRectGetMaxX(pathData.rect),
                                     CGRectGetMinY(pathData.rect));
    CGPoint lowerLeft = CGPointMake(
                                    CGRectGetMinX(pathData.rect),
                                    CGRectGetMaxY(pathData.rect));
    CGPoint lowerRight = CGPointMake(
                                    CGRectGetMaxX(pathData.rect),
                                    CGRectGetMaxY(pathData.rect));
    CGPoint points[kNumCorners] = {upperLeft, upperRight, lowerLeft, lowerRight};
    BBDrawablePathRect *drawableRect = [[BBDrawablePathRect alloc] initWithRect:pathData.rect];
    BBDrawablePath *tempPath = drawableRect;
    for (int i = 0; i < kNumCorners; ++i) {
        tempPath = [self decorateDrawablePath:tempPath withKnot:points[i]];
    }
    return tempPath;
}

和单元测试：

- (void)testVisitBBPathRect
{
    // Given: a drawing visitor and a Rect Path Data to draw
    BBDrawablePathDrawingVisitor *visitor = [BBDrawablePathDrawingVisitor new];
    id pathDataRectMock = [OCMockObject mockForClass:[BBDrawablePathRect class]];
    [[[pathDataRectMock expect] andReturnValue:OCMOCK_VALUE(CGRectMake(0, 0, 0, 0))] rect];
    [[[pathDataRectMock expect] andReturnValue:@YES] isSelected];
    [[pathDataRectMock expect] setBezierPath:[OCMArg any]];
    // When: the visitor draws the path
    id createdPath = [visitor visitBBDrawablePathRect:pathDataRectMock];
    // Then: 
    XCTAssertNotNil(createdPath, @"Visitor should have generated a drawable path");
    XCTAssertTrue([createdPath isKindOfClass:[UIBezierPath class]], @"Drawable path should be a Bezier Path");
    [pathDataRectMock verify];
}

和错误：

Test Case '-[BBPathDataDrawingRepresentationVisitorTests testVisitBBPathRect]' started.
Jan 23 11:08:41 Mercury.local BezierBuilder[1188] <Error>: CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context  and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

Answer 1

您是否首先使用上下文调用UIGraphicsPushContext()？