diff --git a/rivertest/work_unit_wrapper.go b/rivertest/work_unit_wrapper.go
new file mode 100644
index 00000000..1dd3f293
--- /dev/null
+++ b/rivertest/work_unit_wrapper.go
@@ -0,0 +1,66 @@
+package rivertest
+
+import (
+	"context"
+	"encoding/json"
+	"time"
+
+	"github.com/riverqueue/river"
+	"github.com/riverqueue/river/internal/hooklookup"
+	"github.com/riverqueue/river/internal/workunit"
+	"github.com/riverqueue/river/rivertype"
+)
+
+// Everything in this file is duplicated from `./work_unit_wrapper.go`. I looked
+// into deduplicating it, but unfortuntately it's quite difficult/impossible.
+//
+// We can't put it in `internal/` because it depends on top level `river` types
+// so that'd immediately produce a cyclic dependency. The only approach that
+// would work would be to export it from the top-level `river` which `rivertest`
+// could then use, but then we'd be exporting some low-level plumbing for
+// internal use, which isn't worth it.
+//
+// The original sin is that basic types like `Job`, `JobArgs`, `Worker`
+// should've been in `rivertype` instead of the top-level `river`, then anything
+// (including these types) could easily have been refactored to anywhere, but
+// it's too late to do that now.
+//
+// The best thing to do for now is probably just to live with the duplication,
+// so I've removed a todo that used to be here and replaced it with this
+// explanatory comment.
+
+// workUnitFactoryWrapper wraps a Worker to implement workUnitFactory.
+type workUnitFactoryWrapper[T river.JobArgs] struct {
+	worker river.Worker[T]
+}
+
+func (w *workUnitFactoryWrapper[T]) MakeUnit(jobRow *rivertype.JobRow) workunit.WorkUnit {
+	return &wrapperWorkUnit[T]{jobRow: jobRow, worker: w.worker}
+}
+
+// wrapperWorkUnit implements workUnit for a job and Worker.
+type wrapperWorkUnit[T river.JobArgs] struct {
+	job    *river.Job[T] // not set until after UnmarshalJob is invoked
+	jobRow *rivertype.JobRow
+	worker river.Worker[T]
+}
+
+func (w *wrapperWorkUnit[T]) HookLookup(lookup *hooklookup.JobHookLookup) hooklookup.HookLookupInterface {
+	var job T
+	return lookup.ByJobArgs(job)
+}
+
+func (w *wrapperWorkUnit[T]) Middleware() []rivertype.WorkerMiddleware {
+	return w.worker.Middleware(w.jobRow)
+}
+func (w *wrapperWorkUnit[T]) NextRetry() time.Time           { return w.worker.NextRetry(w.job) }
+func (w *wrapperWorkUnit[T]) Timeout() time.Duration         { return w.worker.Timeout(w.job) }
+func (w *wrapperWorkUnit[T]) Work(ctx context.Context) error { return w.worker.Work(ctx, w.job) }
+
+func (w *wrapperWorkUnit[T]) UnmarshalJob() error {
+	w.job = &river.Job[T]{
+		JobRow: w.jobRow,
+	}
+
+	return json.Unmarshal(w.jobRow.EncodedArgs, &w.job.Args)
+}
diff --git a/rivertest/worker.go b/rivertest/worker.go
index c0b9a652..7b8e48fd 100644
--- a/rivertest/worker.go
+++ b/rivertest/worker.go
@@ -2,11 +2,9 @@ package rivertest
 
 import (
 	"context"
-	"encoding/json"
 	"errors"
 	"fmt"
 	"testing"
-	"time"
 
 	"github.com/riverqueue/river"
 	"github.com/riverqueue/river/internal/execution"
@@ -15,7 +13,6 @@ import (
 	"github.com/riverqueue/river/internal/jobexecutor"
 	"github.com/riverqueue/river/internal/maintenance"
 	"github.com/riverqueue/river/internal/middlewarelookup"
-	"github.com/riverqueue/river/internal/workunit"
 	"github.com/riverqueue/river/riverdriver"
 	"github.com/riverqueue/river/rivershared/baseservice"
 	"github.com/riverqueue/river/rivershared/riversharedtest"
@@ -294,41 +291,3 @@ func (h *errorHandlerWrapper) HandleError(ctx context.Context, job *rivertype.Jo
 func (h *errorHandlerWrapper) HandlePanic(ctx context.Context, job *rivertype.JobRow, panicVal any, trace string) *jobexecutor.ErrorHandlerResult {
 	return h.HandlePanicFunc(ctx, job, panicVal, trace)
 }
-
-// TODO: move work_unit_wrapper.go so I don't need to copy paste it here:
-
-// workUnitFactoryWrapper wraps a Worker to implement workUnitFactory.
-type workUnitFactoryWrapper[T river.JobArgs] struct {
-	worker river.Worker[T]
-}
-
-func (w *workUnitFactoryWrapper[T]) MakeUnit(jobRow *rivertype.JobRow) workunit.WorkUnit {
-	return &wrapperWorkUnit[T]{jobRow: jobRow, worker: w.worker}
-}
-
-// wrapperWorkUnit implements workUnit for a job and Worker.
-type wrapperWorkUnit[T river.JobArgs] struct {
-	job    *river.Job[T] // not set until after UnmarshalJob is invoked
-	jobRow *rivertype.JobRow
-	worker river.Worker[T]
-}
-
-func (w *wrapperWorkUnit[T]) HookLookup(lookup *hooklookup.JobHookLookup) hooklookup.HookLookupInterface {
-	var job T
-	return lookup.ByJobArgs(job)
-}
-
-func (w *wrapperWorkUnit[T]) Middleware() []rivertype.WorkerMiddleware {
-	return w.worker.Middleware(w.jobRow)
-}
-func (w *wrapperWorkUnit[T]) NextRetry() time.Time           { return w.worker.NextRetry(w.job) }
-func (w *wrapperWorkUnit[T]) Timeout() time.Duration         { return w.worker.Timeout(w.job) }
-func (w *wrapperWorkUnit[T]) Work(ctx context.Context) error { return w.worker.Work(ctx, w.job) }
-
-func (w *wrapperWorkUnit[T]) UnmarshalJob() error {
-	w.job = &river.Job[T]{
-		JobRow: w.jobRow,
-	}
-
-	return json.Unmarshal(w.jobRow.EncodedArgs, &w.job.Args)
-}