write-go-tests

name	write-go-tests
description	Conventions for writing Go tests in the reearth-cms server (server/) — table-driven tests with t.Parallel(), interactor tests using in-memory repositories, and e2e GraphQL tests. Use when adding or fixing tests for pkg/ domain code, internal/usecase/interactor logic, or e2e/ flows, or when a test is flaky, skipped, or won't compile.

Writing Go tests for the reearth-cms server

Table-driven + parallel (default for everything)

func TestField_Validate(t *testing.T) {
    t.Parallel()
    tests := []struct {
        name    string
        field   *Field
        value   *value.Value
        wantErr bool
    }{
        {name: "required with value", field: ..., value: ..., wantErr: false},
        {name: "required without value", field: ..., value: nil, wantErr: true},
    }
    for _, tt := range tests {
        t.Run(tt.name, func(t *testing.T) {
            t.Parallel()
            err := tt.field.Validate(tt.value)
            if tt.wantErr {
                assert.Error(t, err)
            } else {
                assert.NoError(t, err)
            }
        })
    }
}

Rules:

• t.Parallel() on the parent and each subtest.
• Build fresh test data inside each subtest — no shared mutable state across cases (race detector runs in CI: go test -race).
• Use testify: assert for soft checks, require when later lines depend on the result.

Domain tests (pkg/)

Pure, no I/O. Construct via the builder, exercise methods, assert on results and sentinel errors:

g, err := group.New().NewID().Name("x").Build()
assert.ErrorIs(t, err, id.ErrDuplicatedKey) // compare sentinels with ErrorIs, not string match

Interactor tests (internal/usecase/interactor/)

Use in-memory repositories from internal/infrastructure/memory, not mongo. Build a repo.Container, seed it, run the use case, assert:

db := memory.New()                 // or assemble a repo.Container with memory.NewGroup() etc.
uc := NewGroup(db, nil)
got, err := uc.Create(ctx, interfaces.CreateGroupParam{...}, op)

• Build an *usecase.Operator with the right workspace/project roles to pass permission checks; test the denied path too (interfaces.ErrOperationDenied).
• Memory repos expose an injectable err field — set it to test repository-failure branches.

Mocks

mockgen mocks (regenerated by go generate ./...) exist for repo/gateway interfaces. Prefer memory repos for interactor behavior; reach for mocks only to assert specific call sequences.

e2e tests (e2e/)

Full GraphQL flow via httpexpect. Reference e2e/gql_item_test.go and helpers in e2e/common_test.go (StartServer, StartServerWithRepos, seeders).

⚠️ e2e tests require MongoDB. They skip silently in short mode and need the DB env var:

export REEARTH_CMS_DB='mongodb://localhost:27017/test'
make run-db   # starts the mongo container
go test ./e2e/...

Without REEARTH_CMS_DB set, e2e tests skip rather than fail — easy to mistake for passing.

Running

go test ./pkg/myfeature/...      # one package
make test                         # everything, with -race
go test -run TestName ./path/...  # single test