TOOLS-4278 Convert three smallest GoConvey test files to testify

[autarch]

Establishes the conventions for the rest of the goconvey -> testify
migration:

• One top-level Convey means no subtest; multiple become t.Run. A Convey
  inside a loop is N top-level Conveys, so each case gets its own t.Run.
• Nested Conveys that differ only in data collapse into table-driven
  cases rather than nested subtests.
• require by default, assert where continuing gives more useful output.
• Direct t.Fatal/t.Errorf assertions become require/assert.
• Assertion messages describe the expected behavior, not the failure.

Also removes the repo's only cmp.Diff call and its go-cmp import.

No behavior change.

[autarch]

• TOOLS-4278 Clean up after the testify migration #1090
• TOOLS-4278 Drop the goconvey dependency #1089
• TOOLS-4278 Remove the last GoConvey from the repo #1088
• TOOLS-4278 Convert mongodump oplog, query and view tests to testify #1087
• TOOLS-4278 Convert mongodump BSON and metadata tests to testify #1086
• TOOLS-4278 Remove the last GoConvey from mongofiles #1085
• TOOLS-4278 Convert mongofiles write concern tests to testify #1084
• TOOLS-4278 Remove the last GoConvey from mongorestore #1083
• TOOLS-4278 Convert mongorestore_test.go index tests to testify #1082
• TOOLS-4278 Convert mongorestore options and basic restore tests to testify #1081
• TOOLS-4278 Convert mongorestore oplog tests to testify #1080
• TOOLS-4278 Convert mongorestore filepath tests to testify #1079
• TOOLS-4278 Convert mongorestore metadata and archive tests to testify #1078
• TOOLS-4278 Remove the last GoConvey from mongoimport #1077
• TOOLS-4278 Convert mongoimport TestImportDocuments to testify #1076
• TOOLS-4278 Convert mongoimport validation and reader tests to testify #1075
• TOOLS-4278 Convert mongoimport common tests to testify #1065
• TOOLS-4278 Convert mongoimport typed-fields tests to testify #1064
• TOOLS-4278 Convert mongoimport csv tests to testify #1063
• TOOLS-4278 Convert mongoimport tsv/json tests to testify #1062
• TOOLS-4278 Convert three smallest GoConvey test files to testify #1061 👈 (View in Graphite)
• master

This stack of pull requests is managed by Graphite. Learn more about stacking.

[autarch]

Running the tests for this stack

Two flags matter, and without them you will see failures that look like they belong to this migration but don't.

Pass -tags failpoints

common/failpoint/manager.go is //go:build failpoints; without the tag noop_manager.go compiles instead and DefaultManager.Get always returns false. TestMongoDumpTOOLS2498 and TestFailDuringResharding then fail with nothing to indicate why. This fooled our own baseline for most of the migration — we tracked both as pre-existing failures until we read the build tags.

Run integration packages one at a time, from a clean server

mongodump and mongorestore both use todb/fromdb on the same server, so a plain go test ./... produces a spurious TestMongoDumpBSON failure from the two racing. Use -p 1.

Several integration tests also don't drop their databases, so the suite is not idempotent — a second full run fails in places the first didn't. Clear them in between:

mongo --quiet --port 33333 --eval 'db.getSiblingDB("fromdb").dropDatabase(); db.getSiblingDB("todb").dropDatabase(); db.getSiblingDB("mongoimport_booleantype_test").dropDatabase()'

Putting it together:

TOOLS_TESTING_UNIT=true TOOLS_TESTING_INTEGRATION=true go test -tags failpoints -p 1 -count=1 ./...

Failures that are real and predate this stack

Two tests fail on master as well, and are preserved rather than fixed — this stack is a mechanical refactor, so weak or broken tests were carried over as-is:

• mongorestore / TestReadDumpServerVersionFromArchive — expects db.Version{8,0,16}, gets {8,0,17}. Our local mongod is a git build reporting 8.0.16-353-gb19191c, and the archive round trip normalizes that pre-release suffix inconsistently. Presumably green in CI against a release build.
• mongofiles / TestDefaultWriteConcern — compares a *wcwrapper.WriteConcern against writeconcern.Majority(), which returns a bare *writeconcern.WriteConcern. Different types, so the deep-equal can never pass regardless of the values.

Also worth knowing: mongorestore takes ~30s against a healthy server but we hit one local replica set where it took 650s+ and blew Go's 10-minute package timeout. That reproduces identically on master, so if the package starts taking minutes, suspect the server rather than the tests.

Everything else

Green: mongodump, mongoimport, mongoexport, mongorestore/ns, and the full unit suite across the repo.