diff --git a/core/coreutil/schedule_test.go b/core/coreutil/schedule_test.go
index a4a3613b1..196f5a0d6 100644
--- a/core/coreutil/schedule_test.go
+++ b/core/coreutil/schedule_test.go
@@ -1,41 +1,38 @@
 // Copyright (c) 2018 Yandex LLC. All rights reserved.
 // Use of this source code is governed by a MPL 2.0
 // license that can be found in the LICENSE file.
-// Author: Vladimir Skipor <skipor@yandex-team.ru>
 
 package coreutil
 
 import (
+	"testing"
 	"time"
 
-	. "github.com/onsi/ginkgo"
-	. "github.com/onsi/gomega"
+	"github.com/stretchr/testify/require"
 	"github.com/yandex/pandora/core/schedule"
 )
 
-var _ = Describe("callback on finish schedule", func() {
-	It("callback once", func() {
-		var callbackTimes int
-		wrapped := schedule.NewOnce(1)
-		testee := NewCallbackOnFinishSchedule(wrapped, func() {
-			callbackTimes++
-		})
-		startAt := time.Now()
-		testee.Start(startAt)
-		tx, ok := testee.Next()
-		Expect(ok).To(BeTrue())
-		Expect(tx).To(Equal(startAt))
-		Expect(callbackTimes).To(Equal(0))
+func TestCallbackOnFinishSchedule(t *testing.T) {
+	var callbackTimes int
+	wrapped := schedule.NewOnce(1)
+	testee := NewCallbackOnFinishSchedule(wrapped, func() {
+		callbackTimes++
+	})
+	startAt := time.Now()
+	testee.Start(startAt)
+	tx, ok := testee.Next()
 
-		tx, ok = testee.Next()
-		Expect(ok).To(BeFalse())
-		Expect(tx).To(Equal(startAt))
-		Expect(callbackTimes).To(Equal(1))
+	require.True(t, ok)
+	require.Equal(t, startAt, tx)
+	require.Equal(t, 0, callbackTimes)
 
-		tx, ok = testee.Next()
-		Expect(ok).To(BeFalse())
-		Expect(tx).To(Equal(startAt))
-		Expect(callbackTimes).To(Equal(1))
-	})
+	tx, ok = testee.Next()
+	require.False(t, ok)
+	require.Equal(t, startAt, tx)
+	require.Equal(t, 1, callbackTimes)
 
-})
+	tx, ok = testee.Next()
+	require.False(t, ok)
+	require.Equal(t, startAt, tx)
+	require.Equal(t, 1, callbackTimes)
+}
diff --git a/core/coreutil/waiter_test.go b/core/coreutil/waiter_test.go
index d5629ecc2..75c5a1f56 100644
--- a/core/coreutil/waiter_test.go
+++ b/core/coreutil/waiter_test.go
@@ -1,70 +1,69 @@
 // Copyright (c) 2018 Yandex LLC. All rights reserved.
 // Use of this source code is governed by a MPL 2.0
 // license that can be found in the LICENSE file.
-// Author: Vladimir Skipor <skipor@yandex-team.ru>
 
 package coreutil
 
 import (
 	"context"
+	"testing"
 	"time"
 
-	. "github.com/onsi/ginkgo"
-	. "github.com/onsi/gomega"
+	"github.com/stretchr/testify/require"
 	"github.com/yandex/pandora/core/schedule"
 )
 
-var _ = Describe("waiter", func() {
+func TestWaiter_Unstarted(t *testing.T) {
+	sched := schedule.NewOnce(1)
+	ctx := context.Background()
+	w := NewWaiter(sched, ctx)
+	var i int
+	for ; w.Wait(); i++ {
+	}
+	require.Equal(t, 1, i)
+}
 
-	It("unstarted", func() {
-		sched := schedule.NewOnce(1)
-		ctx := context.Background()
-		w := NewWaiter(sched, ctx)
-		var i int
-		for ; w.Wait(); i++ {
-		}
-		Expect(i).To(BeEquivalentTo(1))
-	})
+func TestWaiter_WaitAsExpected(t *testing.T) {
+	const (
+		duration = 100 * time.Millisecond
+		ops      = 100
+		times    = ops * duration / time.Second
+	)
+	sched := schedule.NewConst(ops, duration)
+	ctx := context.Background()
+	w := NewWaiter(sched, ctx)
+	start := time.Now()
+	sched.Start(start)
+	var i int
+	for ; w.Wait(); i++ {
+	}
+	finish := time.Now()
 
-	It("wait as expected", func() {
-		const (
-			duration = 100 * time.Millisecond
-			ops      = 100
-			times    = ops * duration / time.Second
-		)
-		sched := schedule.NewConst(ops, duration)
-		ctx := context.Background()
-		w := NewWaiter(sched, ctx)
-		start := time.Now()
-		sched.Start(start)
-		var i int
-		for ; w.Wait(); i++ {
-		}
-		finish := time.Now()
-		Expect(i).To(BeEquivalentTo(times))
-		Expect(finish.Sub(start)).To(BeNumerically(">=", duration*(times-1)/times))
-		Expect(finish.Sub(start)).To(BeNumerically("<", 3*duration)) // Smaller interval will be more flaky.
-	})
+	require.Equal(t, int(times), i)
+	dur := finish.Sub(start)
+	require.True(t, dur >= duration*(times-1)/times)
+	require.True(t, dur < 3*duration) // Smaller interval will be more flaky.
+}
+func TestWaiter_ContextCanceledBeforeWait(t *testing.T) {
+	sched := schedule.NewOnce(1)
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	w := NewWaiter(sched, ctx)
+	require.False(t, w.Wait())
+}
 
-	It("context canceled before wait", func() {
-		sched := schedule.NewOnce(1)
-		ctx, cancel := context.WithCancel(context.Background())
-		cancel()
-		w := NewWaiter(sched, ctx)
-		Expect(w.Wait()).To(BeFalse())
-	})
+func TestWaiter_ContextCanceledDuringWait(t *testing.T) {
+	sched := schedule.NewConstConf(schedule.ConstConfig{Ops: 0.1, Duration: 100 * time.Second})
+	timeout := 20 * time.Millisecond
+	start := time.Now()
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+	w := NewWaiter(sched, ctx)
 
-	It("context canceled during wait", func() {
-		sched := schedule.NewConstConf(schedule.ConstConfig{Ops: 0.1, Duration: 100 * time.Second})
-		timeout := 20 * time.Millisecond
-		start := time.Now()
-		ctx, cancel := context.WithTimeout(context.Background(), timeout)
-		defer cancel()
-		w := NewWaiter(sched, ctx)
-		Expect(w.Wait()).To(BeTrue()) // 0
-		Expect(w.Wait()).To(BeFalse())
-		Expect(time.Since(start)).To(BeNumerically(">", timeout))
-		Expect(time.Since(start)).To(BeNumerically("<", 10*timeout))
-	})
+	require.True(t, w.Wait()) // 0
+	require.False(t, w.Wait())
 
-})
+	since := time.Since(start)
+	require.True(t, since > timeout)
+	require.True(t, since < 10*timeout)
+}
diff --git a/core/engine/instance.go b/core/engine/instance.go
index d271f8d63..8c36f3cdd 100644
--- a/core/engine/instance.go
+++ b/core/engine/instance.go
@@ -67,24 +67,18 @@ type instanceSharedDeps struct {
 
 // Run blocks until ammo finish, error or context cancel.
 // Expects, that gun is already bind.
-func (i *instance) Run(ctx context.Context) error {
-	i.log.Debug("Instance started")
-	i.metrics.InstanceStart.Add(1)
-	defer func() {
-		i.metrics.InstanceFinish.Add(1)
-		i.log.Debug("Instance finished")
-	}()
-
-	return i.shoot(ctx)
-}
-
-func (i *instance) shoot(ctx context.Context) (err error) {
+func (i *instance) Run(ctx context.Context) (recoverErr error) {
 	defer func() {
 		r := recover()
 		if r != nil {
-			err = errors.Errorf("shoot panic: %s", r)
+			recoverErr = errors.Errorf("shoot panic: %s", r)
 		}
+
+		i.log.Debug("Instance finished")
+		i.metrics.InstanceFinish.Add(1)
 	}()
+	i.log.Debug("Instance started")
+	i.metrics.InstanceStart.Add(1)
 
 	waiter := coreutil.NewWaiter(i.schedule, ctx)
 	// Checking, that schedule is not finished, required, to not consume extra ammo,