4 files changed, 44 insertions, 5 deletions
diff --git a/workers/error.go b/workers/error.go
index 1b0f7d6..bd51509 100644
--- a/workers/error.go
+++ b/workers/error.go
@@ -30,4 +30,7 @@ var (
 	ErrWorkerNotFound = errors.New("Worker is not present on the list")
 	// ErrInMaintenance is returned when SetFail has been called for Worker in MAINTENANCE state.
 	ErrInMaintenance = errors.New("It is forbidden to set FAIL state when Worker is in MAINTENANCE state")
+	// ErrNotInMaintenance is returned when Deregister is called for a worker not in MAINTENANCE state.
+	// Only workers in MAINTENANCE state can be removed from the list.
+	ErrNotInMaintenance = errors.New("Worker is not in MAINTENANCE state")
 )
diff --git a/workers/worker_list_test.go b/workers/worker_list_test.go
index 562f452..2800cbf 100644
--- a/workers/worker_list_test.go
+++ b/workers/worker_list_test.go
@@ -173,5 +173,37 @@ var _ = Describe("WorkerList", func() {
 				Expect(wl.workers[worker].State).To(Equal(MAINTENANCE))
 			})
 		})
+
+		Describe("Deregister", func() {
+			It("should fail to deregister nonexistent worker", func() {
+				uuid := randomUUID()
+				err := wl.Deregister(uuid)
+				Expect(err).To(Equal(ErrWorkerNotFound))
+			})
+
+			It("should work to deregister", func() {
+				err := wl.Deregister(worker)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(wl.workers).ToNot(HaveKey(worker))
+			})
+
+			It("should fail to deregister same worker twice", func() {
+				err := wl.Deregister(worker)
+				Expect(err).ToNot(HaveOccurred())
+				Expect(wl.workers).ToNot(HaveKey(worker))
+
+				err = wl.Deregister(worker)
+				Expect(err).To(Equal(ErrWorkerNotFound))
+			})
+
+			It("should fail to deregister worker not in MAINTENANCE state", func() {
+				for _, state := range []WorkerState{IDLE, RUN, FAIL} {
+					wl.workers[worker].State = state
+					err := wl.Deregister(worker)
+					Expect(err).To(Equal(ErrNotInMaintenance))
+					Expect(wl.workers).To(HaveKey(worker))
+				}
+			})
+		})
 	})
 })
diff --git a/workers/workers.go b/workers/workers.go
index 3c27582..ff21f09 100644
--- a/workers/workers.go
+++ b/workers/workers.go
@@ -88,7 +88,15 @@ func (wl *WorkerList) SetGroups(uuid WorkerUUID, groups Groups) error {
 
 // Deregister is an implementation of Deregister from Workers interface.
 func (wl *WorkerList) Deregister(uuid WorkerUUID) error {
-	return ErrNotImplemented
+	worker, ok := wl.workers[uuid]
+	if !ok {
+		return ErrWorkerNotFound
+	}
+	if worker.State != MAINTENANCE {
+		return ErrNotInMaintenance
+	}
+	delete(wl.workers, uuid)
+	return nil
 }
 
 // ListWorkers is an implementation of ListWorkers from Workers interface.
diff --git a/workers/workers_test.go b/workers/workers_test.go
index c6cc3e6..dc2fed5 100644
--- a/workers/workers_test.go
+++ b/workers/workers_test.go
@@ -46,10 +46,6 @@ var _ = Describe("WorkerList", func() {
 		err = wl.SetGroups(uuid, groups)
 		Expect(err).To(Equal(ErrNotImplemented))
 
-		By("Deregister")
-		err = wl.Deregister(uuid)
-		Expect(err).To(Equal(ErrNotImplemented))
-
 		By("ListWorkers")
 		_, err = wl.ListWorkers(groups, caps)
 		Expect(err).To(Equal(ErrNotImplemented))