[SemVer2] Filter SemVer v2.0.0 package versions by default on v1 and v2 OData endpoints

[xavierdecoster]

This PR is NOT about adding support for the new semVerLevel parameter... yet! Not on the gallery endpoints, and not on the calls to the search service. That work is tracked by #3557.

This PR is about filtering out all SemVer v2.0.0 package versions by default on all requests to v1 and v2 endpoints.

These changes should be all that is needed to ensure default filtering behavior to avoid client-side issues with clients that do not support the NuGet SemVer 2.0.0 protocol (i.e. clients that don't send the semVerLevel=2.0.0 query string parameter)

[skofman1]

[xavierdecoster]

@joelverhagen @scottbommarito @ryuyu need more squirrels :)

[scottbommarito]

I see this code repeated in many test cases. You could easily reduce this by creating a helper function that takes in a TFeedPackage...

public void AssertResultCorrect(TFeedPackage feedPackage)
{
    // Assert none of the items in the result set are SemVer v.2.0.0 packages (checking on original version is enough in this case)
    Assert.Empty(SemVer2Packages.Where(p => string.Equals(p.Version, feedPackage.Version)));
    
    // Assert each of the items in the result set is a non-SemVer v2.0.0 package
    Assert.Single(NonSemVer2Packages.Where(p =>
                string.Equals(p.Version, feedPackage.Version) &&
                string.Equals(p.PackageRegistration.Id, feedPackage.Id)));
}

[Fact]
public async Task Get_FiltersSemVerV2PackageVersions()
{
    // Act
    var resultSet = await GetCollection<V1FeedPackage>(
        (controller, options) => controller.Get(options),
        "/api/v1/Packages");

    // Assert
    resultSet.Select(AssertResultCorrect);
}

[xavierdecoster]

Yep, missed that one during clean up :) Addressed with 6be4a72

[scottbommarito]

I wish there was an easier way to add conditions here rather than having to change every place where we query the packages repository.

Do you think we could extract these checks out to a function?

public static bool ShouldShowPackage(V1FeedPackage package, bool showUnlisted)
{
    return !package.IsPrerelease && !package.Deleted && package.SemVerLevelKey == SemVerLevelKey.Unknown && (showUnlisted || package.IsListed);
}

You could add this as a method in the base class (NuGetODataController) and use it in ODataV2FeedController as well.

[xavierdecoster]

I was thinking about consolidating this somehow too, however, the logic is not the same for v1 and v2. E.g. v1 also filters out pre-release packages from the feed.