add unit tests for the clusterinfo package

[abrarshivani]

clusterinfo answers questions about the cluster the operator runs in: which container
runtime the GPU nodes use, whether this is OpenShift and at what version, whether there is
a cluster-wide proxy, and whether the cluster supports DRA. Other parts of the operator use
those answers to decide what to install and how to configure it, so a wrong answer here is
quiet and hard to trace.

#2831 added tests for getRuntimeString. The rest of the package had none. This adds them.
No production code is changed.

How the tests work

clusterinfo builds its typed clients inside each function from a *rest.Config, so there
is no seam to inject a fake through. The tests point rest.Config at an httptest server
that serves the endpoints the package reads: nodes, ClusterVersion, Proxy, the
driver-toolkit ImageStream, and API discovery. Real client-go runs against it, so URL
building, decoding and 404 handling are exercised rather than simulated. That matters here
because getOpenshiftVersion and getOpenshiftProxySpec treat a 404 in opposite ways, and
the apierrors.IsNotFound mapping is part of the behaviour under test.

The stub fails a test if a client requests a path it has no handler for. Without that a
wrong URL returns 404, getOpenshiftVersion reads 404 as "not OpenShift", and the test
passes for the wrong reason. That check is what caught the DRA discovery calls when this
branch was rebased forward.

The cost worth knowing about: these tests are coupled to client-go behaviour that is not an
API contract — the discovery fan-out, the fact that a 5xx without Retry-After is not
retried, and protobuf-vs-JSON content negotiation. Each of those is commented where it is
relied on, so a k8s.io/* bump that changes them should fail loudly rather than silently.

getRuntimeString keeps all five cases from #2831 and gains three: a bare prefix with no
version suffix, a runtime name appearing as a substring rather than a prefix, and case
sensitivity. They move from clusterinfo_test.go into runtime_test.go, which now holds
every test for the container runtime path. That move is why the diff shows deletions in a
file this branch did not create.

Coverage is 99.3% of statements. The uncovered line is the config.GetConfigOrDie()
fallback in New, which calls os.Exit.

Behaviour that looks wrong

Nine behaviours look like bugs. None are fixed here. The tests record what the code does
today and live in clusterinfo_characterization_test.go, apart from the tests asserting
intended behaviour, so fixing any one of them fails only tests in that file — a maintainer
sees "I improved this" rather than "I broke this". That property is checked by applying each
fix and confirming where the failures land, not assumed.

Each is a numbered comment in that file. Happy to split any of these into their own issue
and fix them separately; I kept them out of this PR so it stays test-only.

Can affect a running cluster

1. getContainerRuntime discards the error from getOpenshiftVersion and continues with the
   empty version it got back, so the crio short-circuit is skipped. An apiserver failure
   shows up only as a "failed to retrieve" log line and the function returns a runtime as
   though the read succeeded.
2. getOpenshiftDTKImages logs the NotFound case and then falls through to logger.Error
   instead of returning, so every driver reconcile on plain Kubernetes logs an error for an
   ImageStream that only exists on OpenShift.
3. getDRAResourceGVR scans every API group for Kind DeviceClass before narrowing to
   resource.k8s.io. An unrelated CRD using that Kind makes a cluster with no DRA fail its
   reconcile with "could not determine the GVR" instead of the message telling the operator
   to enable Dynamic Resource Allocation.
4. getDRAResourceGVR treats any ErrGroupDiscoveryFailed as recoverable without checking
   which group failed. If resource.k8s.io itself is unreachable the result is "DRA not
   supported" with a nil error, and the reconcile renders as if the cluster has no DRA.
5. getOpenshiftVersion returns ("", nil) for a Completed history entry with an empty
   version — the same value that means "not OpenShift". The upstream field is documented as
   optionally empty, so this is reachable on a real cluster.
6. getContainerRuntime stops its node scan only for containerd. On a cluster mixing docker
   and cri-o nodes the answer is whichever the apiserver listed last, which flips whether the
   RHSM subscription paths get mounted into the driver container.

Latent

cmd/gpu-operator/main.go builds clusterinfo with WithOneShot(false), so these cannot be
reached today.

4. getOpenshiftProxySpec logs the error from ocpconfigv1.NewForConfig without returning
   it, so a nil client reaches Proxies().Get and panics. It needs a rest.Config the
   constructor rejects, and mgr.GetConfig() never is.
5. New's oneshot path never fetches the proxy, so GetOpenshiftProxySpec reports none for
   the instance's lifetime and a configured cluster Proxy would drop out of the rendered
   driver DaemonSet.
6. GetOpenshiftDriverToolkitImages hands back the cached map itself rather than a copy. No
   caller mutates it today.

Verification

make check and the package tests pass under the toolchain in versions.mk (Go 1.27.1,
golangci-lint v2.13.1) on Linux, with the repo's own .golangci.yml: 0 issues. The suite is
clean under -race and -shuffle=on, and every test and subtest also passes when run in its
own process.

[coderabbitai]

📝 Walkthrough

Walkthrough

Added comprehensive cluster information tests. The changes add HTTP API stubs, discovery fixtures, structured log capture, and typed resource builders. Tests cover runtime detection, New initialization, context and option handling, OpenShift version detection, DRA discovery, proxy retrieval, Driver Toolkit image lookup, request ordering, error propagation, caching, and returned-value mutation behavior.

Priority: ⬇️ Low

Merge Risk: 🔵 Low · up to d35f2

The PR is mergeable with low risk, but two test assertions should be strengthened to ensure future regressions in diagnostics and DRA initialization are detected.

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[coderabbitai]

Note

Quiet mode is enabled, so only the most important comments were posted inline. Other review comments are grouped below.

🟡 Other comments (2)

controllers/clusterinfo/clusterinfo_characterization_test.go-237-244 (1)

237-244: 📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

The cache assertion can pass with a zero baseline.

groupListRequestCountDuringNew is used only as the expected length. If New stops running discovery, the baseline is 0 and require.Len compares 0 against 0. The test then reports that the oneshot verdict is cached while no discovery ran at all, and draSupported is false in both worlds.

Pin the baseline so the caching claim needs a real request to have happened during New.

Assert the baseline

 	groupListRequestCountDuringNew := len(apiServer.requestsTo(pathAPIGroups))
+	require.NotZero(t, groupListRequestCountDuringNew,
+		"New must have run discovery for the cached verdict to mean anything")

As per path instructions: "Flag assertions that would still pass if the behavior under test were broken."

Source: Path instructions

controllers/clusterinfo/openshift_dtk_test.go-95-104 (1)

95-104: 📐 Maintainability & Code Quality | 🟡 Minor | ⚡ Quick win

Assert the remaining Driver Toolkit diagnostics. The empty-name case only checks the returned map, so removing the RHBZ#2015024 logger.Info call leaves it green. The client-construction case only checks nil, so removing failed to build openshift image stream client also leaves it green. Capture logs with testContextWithCapturedLogs and assert both messages.

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📥 Commits

Reviewing files that changed from the base of the PR and between 6e330ac and d35f2d9.

📒 Files selected for processing (9)

• controllers/clusterinfo/clusterinfo_characterization_test.go
• controllers/clusterinfo/clusterinfo_test.go
• controllers/clusterinfo/dra_test.go
• controllers/clusterinfo/logging_test.go
• controllers/clusterinfo/openshift_dtk_test.go
• controllers/clusterinfo/openshift_proxy_test.go
• controllers/clusterinfo/openshift_version_test.go
• controllers/clusterinfo/runtime_test.go
• controllers/clusterinfo/stubs_test.go

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