Add dag-scope tests

[guanzo]

TODO:

• Add a fixture that supports comprehensive car-scope tests.
• Rename car-scope to dag-scope once lassie supports it.

How I generated the fixture

#!/bin/bash

# set kubo config "Internal.UnixFSShardingSizeThreshold": "10B"

mkdir -p dir/sub1
echo "abc123" > dir/sub1/hello.txt
mkdir -p dir/sub2
echo "xyz456" > dir/sub2/hello.txt

ROOT_CID=$(ipfs add -Qr --chunker=size-5 dir)

ipfs dag export ${ROOT_CID} > ./t0118-ipip-402-scope.car

The point of 2 subdirectories is that if the request is for one of them (/sub1/hello.txt), than the other (/sub2) should not appear in the CAR.

[laurentsenta]

Adding related contributors for review, the code looks fine to me;
Could you rebase over the latest main? It looks like it shows the car tooling changes that are already in main.

[guanzo]

Had trouble doing a clean rebase so force pushed instead 😅

[galargh]

The tests haven't been running on this PR because we had a wrong trigger configured for the job. This is being fixed in #60

In the meantime, I pushed https://github.com/ipfs/gateway-conformance/tree/guanzo-main so that we get CI runs for the HEAD of this PR. Unfortunately, it looks like the newly added tests aren't passing when running against kubo-master. See https://github.com/ipfs/gateway-conformance/actions/runs/5119205028/attempts/1#summary-13852714693

[guanzo]

The failures are due to kubo not "returning intermediate blocks from the CID root to the path terminus as part of the returned CAR file" as mentioned in this PR. ipfs/specs#402. Not sure how we want to proceed as idk when kubo will implement that.

[galargh]

We can skip the some expects like this:

gateway-conformance/.github/workflows/test.yml

Line 65 in 2648070

args: -skip 'TestGatewayCar/GET_response_for_application/vnd.ipld.car/Header_Content-Length'

[guanzo]

I can skip the CAR cid checks but that basically skips all tests added by this PR 😆 . We can do that or skip the intermediate cid checks for now.

[hacdias]

I'm closing this and we'll continue on #56. Thanks @guanzo for your contribution on this. Changes are included in #56.