public void SetUp()
{
this.upgradeDirectory = ProductUpgraderInfo.GetHighestAvailableVersionDirectory();
this.expectedNewVersionExistsFilePath = Path.Combine(this.upgradeDirectory, this.expectedNewVersionExistsFileName);
this.mockFileSystem = new Mock <PhysicalFileSystem>();
this.mockFileSystem.Setup(fileSystem => fileSystem.WriteAllText(this.expectedNewVersionExistsFilePath, It.IsAny <string>()));
this.tracer = new MockTracer();
this.productUpgraderInfo = new ProductUpgraderInfo(
this.tracer,
this.mockFileSystem.Object);
}