From 005be1dd55b27e8428a05ac3e93bce852f121212 Mon Sep 17 00:00:00 2001
From: Spike Curtis <spike@coder.com>
Date: Fri, 7 Jun 2024 11:33:14 +0400
Subject: [PATCH] chore: change mock clock to allow Advance() within timer/tick
 functions

---
 clock/clock.go                              |   2 +
 clock/example_test.go                       |  69 +++++-
 clock/mock.go                               | 226 ++++++++++++--------
 clock/real.go                               |   4 +
 clock/timer.go                              |  16 +-
 coderd/database/pubsub/watchdog_test.go     |  26 ++-
 enterprise/tailnet/pgcoord.go               |  80 +++----
 enterprise/tailnet/pgcoord_internal_test.go | 132 +++++++++---
 enterprise/tailnet/pgcoord_test.go          |  45 ++--
 tailnet/configmaps_internal_test.go         |  41 ++--
 10 files changed, 424 insertions(+), 217 deletions(-)

diff --git a/clock/clock.go b/clock/clock.go
index 516b74e6b117b..5f3b0de105911 100644
--- a/clock/clock.go
+++ b/clock/clock.go
@@ -26,6 +26,8 @@ type Clock interface {
 	Now(tags ...string) time.Time
 	// Since returns the time elapsed since t. It is shorthand for Clock.Now().Sub(t).
 	Since(t time.Time, tags ...string) time.Duration
+	// Until returns the duration until t. It is shorthand for t.Sub(Clock.Now()).
+	Until(t time.Time, tags ...string) time.Duration
 }
 
 // Waiter can be waited on for an error.
diff --git a/clock/example_test.go b/clock/example_test.go
index 69d6ba4a318ae..de72312d7d036 100644
--- a/clock/example_test.go
+++ b/clock/example_test.go
@@ -44,7 +44,7 @@ func TestExampleTickerFunc(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 
 	// Because the ticker is started on a goroutine, we can't immediately start
 	// advancing the clock, or we will race with the start of the ticker. If we
@@ -76,9 +76,74 @@ func TestExampleTickerFunc(t *testing.T) {
 	}
 
 	// Now that we know the ticker is started, we can advance the time.
-	mClock.Advance(time.Hour).MustWait(ctx, t)
+	mClock.Advance(time.Hour).MustWait(ctx)
 
 	if tks := tc.Ticks(); tks != 1 {
 		t.Fatalf("expected 1 got %d ticks", tks)
 	}
 }
+
+type exampleLatencyMeasurer struct {
+	mu          sync.Mutex
+	lastLatency time.Duration
+}
+
+func newExampleLatencyMeasurer(ctx context.Context, clk clock.Clock) *exampleLatencyMeasurer {
+	m := &exampleLatencyMeasurer{}
+	clk.TickerFunc(ctx, 10*time.Second, func() error {
+		start := clk.Now()
+		// m.doSomething()
+		latency := clk.Since(start)
+		m.mu.Lock()
+		defer m.mu.Unlock()
+		m.lastLatency = latency
+		return nil
+	})
+	return m
+}
+
+func (m *exampleLatencyMeasurer) LastLatency() time.Duration {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	return m.lastLatency
+}
+
+func TestExampleLatencyMeasurer(t *testing.T) {
+	t.Parallel()
+
+	// nolint:gocritic // trying to avoid Coder-specific stuff with an eye toward spinning this out
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	mClock := clock.NewMock(t)
+	trap := mClock.Trap().Since()
+	defer trap.Close()
+
+	lm := newExampleLatencyMeasurer(ctx, mClock)
+
+	w := mClock.Advance(10 * time.Second) // triggers first tick
+	c := trap.MustWait(ctx)               // call to Since()
+	mClock.Advance(33 * time.Millisecond)
+	c.Release()
+	w.MustWait(ctx)
+
+	if l := lm.LastLatency(); l != 33*time.Millisecond {
+		t.Fatalf("expected 33ms got %s", l.String())
+	}
+
+	// Next tick is in 10s - 33ms, but if we don't want to calculate, we can use:
+	d, w2 := mClock.AdvanceNext()
+	c = trap.MustWait(ctx)
+	mClock.Advance(17 * time.Millisecond)
+	c.Release()
+	w2.MustWait(ctx)
+
+	expectedD := 10*time.Second - 33*time.Millisecond
+	if d != expectedD {
+		t.Fatalf("expected %s got %s", expectedD.String(), d.String())
+	}
+
+	if l := lm.LastLatency(); l != 17*time.Millisecond {
+		t.Fatalf("expected 17ms got %s", l.String())
+	}
+}
diff --git a/clock/mock.go b/clock/mock.go
index 55c8cdcaa3277..6e66206c1614d 100644
--- a/clock/mock.go
+++ b/clock/mock.go
@@ -3,6 +3,7 @@ package clock
 import (
 	"context"
 	"errors"
+	"fmt"
 	"slices"
 	"sync"
 	"testing"
@@ -12,13 +13,11 @@ import (
 // Mock is the testing implementation of Clock.  It tracks a time that monotonically increases
 // during a test, triggering any timers or tickers automatically.
 type Mock struct {
+	tb testing.TB
 	mu sync.Mutex
 
 	// cur is the current time
 	cur time.Time
-	// advancing is true when we are in the process of advancing the clock.  We don't support
-	// multiple goroutines doing this at once.
-	advancing bool
 
 	all        []event
 	nextTime   time.Time
@@ -77,11 +76,9 @@ func (m *Mock) AfterFunc(d time.Duration, f func(), tags ...string) *Timer {
 	}
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	m.matchCallLocked(&Call{
-		fn:       clockFunctionAfterFunc,
-		Duration: d,
-		Tags:     tags,
-	})
+	c := newCall(clockFunctionAfterFunc, tags, withDuration(d))
+	defer close(c.complete)
+	m.matchCallLocked(c)
 	t := &Timer{
 		nxt:  m.cur.Add(d),
 		fn:   f,
@@ -94,23 +91,30 @@ func (m *Mock) AfterFunc(d time.Duration, f func(), tags ...string) *Timer {
 func (m *Mock) Now(tags ...string) time.Time {
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	m.matchCallLocked(&Call{
-		fn:   clockFunctionNow,
-		Tags: tags,
-	})
+	c := newCall(clockFunctionNow, tags)
+	defer close(c.complete)
+	m.matchCallLocked(c)
 	return m.cur
 }
 
 func (m *Mock) Since(t time.Time, tags ...string) time.Duration {
 	m.mu.Lock()
 	defer m.mu.Unlock()
-	m.matchCallLocked(&Call{
-		fn:   clockFunctionSince,
-		Tags: tags,
-	})
+	c := newCall(clockFunctionSince, tags, withTime(t))
+	defer close(c.complete)
+	m.matchCallLocked(c)
 	return m.cur.Sub(t)
 }
 
+func (m *Mock) Until(t time.Time, tags ...string) time.Duration {
+	m.mu.Lock()
+	defer m.mu.Unlock()
+	c := newCall(clockFunctionUntil, tags, withTime(t))
+	defer close(c.complete)
+	m.matchCallLocked(c)
+	return t.Sub(m.cur)
+}
+
 func (m *Mock) addTimerLocked(t *Timer) {
 	m.all = append(m.all, t)
 	m.recomputeNextLocked()
@@ -182,14 +186,15 @@ func (m *Mock) matchCallLocked(c *Call) {
 	m.mu.Lock()
 }
 
-// AdvanceWaiter is returned from Advance and Set calls and allows you to wait for:
-//
-//   - tick functions of tickers created using NewContextTicker
-//   - functions passed to AfterFunc
+// AdvanceWaiter is returned from Advance and Set calls and allows you to wait for ticks and timers
+// to complete.  In the case of functions passed to AfterFunc or TickerFunc, it waits for the
+// functions to return.  For other ticks & timers, it just waits for the tick to be delivered to
+// the channel.
 //
-// to complete. If multiple timers or tickers trigger simultaneously, they are all run on separate
+// If multiple timers or tickers trigger simultaneously, they are all run on separate
 // go routines.
 type AdvanceWaiter struct {
+	tb testing.TB
 	ch chan struct{}
 }
 
@@ -206,12 +211,13 @@ func (w AdvanceWaiter) Wait(ctx context.Context) error {
 // MustWait waits for all timers and ticks to complete, and fails the test immediately if the
 // context completes first.  MustWait must be called from the goroutine running the test or
 // benchmark, similar to `t.FailNow()`.
-func (w AdvanceWaiter) MustWait(ctx context.Context, t testing.TB) {
+func (w AdvanceWaiter) MustWait(ctx context.Context) {
+	w.tb.Helper()
 	select {
 	case <-w.ch:
 		return
 	case <-ctx.Done():
-		t.Fatalf("context expired while waiting for clock to advance: %s", ctx.Err())
+		w.tb.Fatalf("context expired while waiting for clock to advance: %s", ctx.Err())
 	}
 }
 
@@ -221,81 +227,112 @@ func (w AdvanceWaiter) Done() <-chan struct{} {
 }
 
 // Advance moves the clock forward by d, triggering any timers or tickers.  The returned value can
-// be used to wait for all timers and ticks to complete.
+// be used to wait for all timers and ticks to complete.  Advance sets the clock forward before
+// returning, and can only advance up to the next timer or tick event. It will fail the test if you
+// attempt to advance beyond.
+//
+// If you need to advance exactly to the next event, and don't know or don't wish to calculate it,
+// consider AdvanceNext().
 func (m *Mock) Advance(d time.Duration) AdvanceWaiter {
-	w := AdvanceWaiter{ch: make(chan struct{})}
-	go func() {
-		defer close(w.ch)
-		m.mu.Lock()
-		defer m.mu.Unlock()
-		m.advanceLocked(d)
-	}()
-	return w
-}
-
-func (m *Mock) advanceLocked(d time.Duration) {
-	if m.advancing {
-		panic("multiple simultaneous calls to Advance/Set not supported")
-	}
-	m.advancing = true
-	defer func() {
-		m.advancing = false
-	}()
-
+	m.tb.Helper()
+	w := AdvanceWaiter{tb: m.tb, ch: make(chan struct{})}
+	m.mu.Lock()
 	fin := m.cur.Add(d)
-	for {
-		// nextTime.IsZero implies no events scheduled
-		if m.nextTime.IsZero() || m.nextTime.After(fin) {
-			m.cur = fin
-			return
-		}
-
-		if m.nextTime.After(m.cur) {
-			m.cur = m.nextTime
-		}
-
-		wg := sync.WaitGroup{}
-		for i := range m.nextEvents {
-			e := m.nextEvents[i]
-			t := m.cur
-			wg.Add(1)
-			go func() {
-				e.fire(t)
-				wg.Done()
-			}()
-		}
-		// release the lock and let the events resolve.  This allows them to call back into the
-		// Mock to query the time or set new timers.  Each event should remove or reschedule
-		// itself from nextEvents.
+	// nextTime.IsZero implies no events scheduled.
+	if m.nextTime.IsZero() || fin.Before(m.nextTime) {
+		m.cur = fin
+		m.mu.Unlock()
+		close(w.ch)
+		return w
+	}
+	if fin.After(m.nextTime) {
+		m.tb.Errorf(fmt.Sprintf("cannot advance %s which is beyond next timer/ticker event in %s",
+			d.String(), m.nextTime.Sub(m.cur)))
 		m.mu.Unlock()
-		wg.Wait()
-		m.mu.Lock()
+		close(w.ch)
+		return w
 	}
+
+	m.cur = m.nextTime
+	go m.advanceLocked(w)
+	return w
+}
+
+func (m *Mock) advanceLocked(w AdvanceWaiter) {
+	defer close(w.ch)
+	wg := sync.WaitGroup{}
+	for i := range m.nextEvents {
+		e := m.nextEvents[i]
+		t := m.cur
+		wg.Add(1)
+		go func() {
+			e.fire(t)
+			wg.Done()
+		}()
+	}
+	// release the lock and let the events resolve.  This allows them to call back into the
+	// Mock to query the time or set new timers.  Each event should remove or reschedule
+	// itself from nextEvents.
+	m.mu.Unlock()
+	wg.Wait()
 }
 
 // Set the time to t.  If the time is after the current mocked time, then this is equivalent to
 // Advance() with the difference.  You may only Set the time earlier than the current time before
 // starting tickers and timers (e.g. at the start of your test case).
 func (m *Mock) Set(t time.Time) AdvanceWaiter {
-	w := AdvanceWaiter{ch: make(chan struct{})}
-	go func() {
+	m.tb.Helper()
+	w := AdvanceWaiter{tb: m.tb, ch: make(chan struct{})}
+	m.mu.Lock()
+	if t.Before(m.cur) {
 		defer close(w.ch)
-		m.mu.Lock()
 		defer m.mu.Unlock()
-		if t.Before(m.cur) {
-			// past
-			if !m.nextTime.IsZero() {
-				panic("Set mock clock to the past after timers/tickers started")
-			}
-			m.cur = t
-			return
+		// past
+		if !m.nextTime.IsZero() {
+			m.tb.Error("Set mock clock to the past after timers/tickers started")
 		}
-		// future, just advance as normal.
-		m.advanceLocked(t.Sub(m.cur))
-	}()
+		m.cur = t
+		return w
+	}
+	// future
+	// nextTime.IsZero implies no events scheduled.
+	if m.nextTime.IsZero() || t.Before(m.nextTime) {
+		defer close(w.ch)
+		defer m.mu.Unlock()
+		m.cur = t
+		return w
+	}
+	if t.After(m.nextTime) {
+		defer close(w.ch)
+		defer m.mu.Unlock()
+		m.tb.Errorf("cannot Set time to %s which is beyond next timer/ticker event at %s",
+			t.String(), m.nextTime)
+		return w
+	}
+
+	m.cur = m.nextTime
+	go m.advanceLocked(w)
 	return w
 }
 
+// AdvanceNext advances the clock to the next timer or tick event.  It fails the test if there are
+// none scheduled.  It returns the duration the clock was advanced and a waiter that can be used to
+// wait for the timer/tick event(s) to finish.
+func (m *Mock) AdvanceNext() (time.Duration, AdvanceWaiter) {
+	m.mu.Lock()
+	m.tb.Helper()
+	w := AdvanceWaiter{tb: m.tb, ch: make(chan struct{})}
+	if m.nextTime.IsZero() {
+		defer close(w.ch)
+		defer m.mu.Unlock()
+		m.tb.Error("cannot AdvanceNext because there are no timers or tickers running")
+	}
+	d := m.nextTime.Sub(m.cur)
+	m.cur = m.nextTime
+	go m.advanceLocked(w)
+	return d, w
+}
+
 // Trapper allows the creation of Traps
 type Trapper struct {
 	// mock is the underlying Mock.  This is a thin wrapper around Mock so that
@@ -335,6 +372,10 @@ func (t Trapper) Since(tags ...string) *Trap {
 	return t.mock.newTrap(clockFunctionSince, tags)
 }
 
+func (t Trapper) Until(tags ...string) *Trap {
+	return t.mock.newTrap(clockFunctionUntil, tags)
+}
+
 func (m *Mock) Trap() Trapper {
 	return Trapper{m}
 }
@@ -356,12 +397,13 @@ func (m *Mock) newTrap(fn clockFunction, tags []string) *Trap {
 // NewMock creates a new Mock with the time set to midnight UTC on Jan 1, 2024.
 // You may re-set the time earlier than this, but only before timers or tickers
 // are created.
-func NewMock() *Mock {
+func NewMock(tb testing.TB) *Mock {
 	cur, err := time.Parse(time.RFC3339, "2024-01-01T00:00:00Z")
 	if err != nil {
 		panic(err)
 	}
 	return &Mock{
+		tb:  tb,
 		cur: cur,
 	}
 }
@@ -387,15 +429,12 @@ func (m *mockTickerFunc) next() time.Time {
 	return m.nxt
 }
 
-func (m *mockTickerFunc) fire(t time.Time) {
+func (m *mockTickerFunc) fire(_ time.Time) {
 	m.mock.mu.Lock()
 	defer m.mock.mu.Unlock()
 	if m.done {
 		return
 	}
-	if !m.nxt.Equal(t) {
-		panic("mockTickerFunc fired at wrong time")
-	}
 	m.nxt = m.nxt.Add(m.d)
 	m.mock.recomputeNextLocked()
 
@@ -449,6 +488,7 @@ const (
 	clockFunctionTickerFuncWait
 	clockFunctionNow
 	clockFunctionSince
+	clockFunctionUntil
 )
 
 type callArg func(c *Call)
@@ -468,7 +508,6 @@ func (c *Call) Release() {
 	<-c.complete
 }
 
-// nolint: unused // it will be soon
 func withTime(t time.Time) callArg {
 	return func(c *Call) {
 		c.Time = t
@@ -544,3 +583,14 @@ func (t *Trap) Wait(ctx context.Context) (*Call, error) {
 		return c, nil
 	}
 }
+
+// MustWait calls Wait() and then if there is an error, immediately fails the
+// test via tb.Fatalf()
+func (t *Trap) MustWait(ctx context.Context) *Call {
+	t.mock.tb.Helper()
+	c, err := t.Wait(ctx)
+	if err != nil {
+		t.mock.tb.Fatalf("context expired while waiting for trap: %s", err.Error())
+	}
+	return c
+}
diff --git a/clock/real.go b/clock/real.go
index e31c80616d896..41019571e6aea 100644
--- a/clock/real.go
+++ b/clock/real.go
@@ -68,4 +68,8 @@ func (realClock) Since(t time.Time, _ ...string) time.Duration {
 	return time.Since(t)
 }
 
+func (realClock) Until(t time.Time, _ ...string) time.Duration {
+	return time.Until(t)
+}
+
 var _ Clock = realClock{}
diff --git a/clock/timer.go b/clock/timer.go
index ee1d67485219d..b2175c953f0d5 100644
--- a/clock/timer.go
+++ b/clock/timer.go
@@ -14,9 +14,6 @@ type Timer struct {
 }
 
 func (t *Timer) fire(tt time.Time) {
-	if !tt.Equal(t.nxt) {
-		panic("mock timer fired at wrong time")
-	}
 	t.mock.removeTimer(t)
 	if t.fn != nil {
 		t.fn()
@@ -56,13 +53,20 @@ func (t *Timer) Reset(d time.Duration, tags ...string) bool {
 	t.mock.matchCallLocked(c)
 	defer close(c.complete)
 	result := !t.stopped
-	t.mock.removeTimerLocked(t)
-	t.stopped = false
-	t.nxt = t.mock.cur.Add(d)
 	select {
 	case <-t.c:
 	default:
 	}
+	if d == 0 {
+		// zero duration timer means we should immediately re-fire it, rather
+		// than remove and re-add it.
+		t.stopped = false
+		go t.fire(t.mock.cur)
+		return result
+	}
+	t.mock.removeTimerLocked(t)
+	t.stopped = false
+	t.nxt = t.mock.cur.Add(d)
 	t.mock.addTimerLocked(t)
 	return result
 }
diff --git a/coderd/database/pubsub/watchdog_test.go b/coderd/database/pubsub/watchdog_test.go
index 62d51c8ecaaee..942f9eeb849c4 100644
--- a/coderd/database/pubsub/watchdog_test.go
+++ b/coderd/database/pubsub/watchdog_test.go
@@ -16,7 +16,7 @@ import (
 func TestWatchdog_NoTimeout(t *testing.T) {
 	t.Parallel()
 	ctx := testutil.Context(t, testutil.WaitShort)
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	logger := slogtest.Make(t, &slogtest.Options{IgnoreErrors: true}).Leveled(slog.LevelDebug)
 	fPS := newFakePubsub()
 
@@ -42,11 +42,13 @@ func TestWatchdog_NoTimeout(t *testing.T) {
 
 	// 5 min / 15 sec = 20, so do 21 ticks
 	for i := 0; i < 21; i++ {
-		mClock.Advance(15*time.Second).MustWait(ctx, t)
+		d, w := mClock.AdvanceNext()
+		w.MustWait(ctx)
+		require.LessOrEqual(t, d, 15*time.Second)
 		p := testutil.RequireRecvCtx(ctx, t, fPS.pubs)
 		require.Equal(t, pubsub.EventPubsubWatchdog, p)
-		mClock.Advance(30*time.Millisecond). // reasonable round-trip
-							MustWait(ctx, t)
+		mClock.Advance(30 * time.Millisecond). // reasonable round-trip
+							MustWait(ctx)
 		// forward the beat
 		sub.listener(ctx, []byte{})
 		// we shouldn't time out
@@ -72,11 +74,11 @@ func TestWatchdog_NoTimeout(t *testing.T) {
 func TestWatchdog_Timeout(t *testing.T) {
 	t.Parallel()
 	ctx := testutil.Context(t, testutil.WaitShort)
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	logger := slogtest.Make(t, &slogtest.Options{IgnoreErrors: true}).Leveled(slog.LevelDebug)
 	fPS := newFakePubsub()
 
-	// trap the ticker and timer calls
+	// trap the ticker calls
 	pubTrap := mClock.Trap().TickerFunc("publish")
 	defer pubTrap.Close()
 
@@ -96,11 +98,13 @@ func TestWatchdog_Timeout(t *testing.T) {
 
 	// 5 min / 15 sec = 20, so do 19 ticks without timing out
 	for i := 0; i < 19; i++ {
-		mClock.Advance(15*time.Second).MustWait(ctx, t)
+		d, w := mClock.AdvanceNext()
+		w.MustWait(ctx)
+		require.LessOrEqual(t, d, 15*time.Second)
 		p := testutil.RequireRecvCtx(ctx, t, fPS.pubs)
 		require.Equal(t, pubsub.EventPubsubWatchdog, p)
-		mClock.Advance(30*time.Millisecond). // reasonable round-trip
-							MustWait(ctx, t)
+		mClock.Advance(30 * time.Millisecond). // reasonable round-trip
+							MustWait(ctx)
 		// we DO NOT forward the heartbeat
 		// we shouldn't time out
 		select {
@@ -110,7 +114,9 @@ func TestWatchdog_Timeout(t *testing.T) {
 			// OK!
 		}
 	}
-	mClock.Advance(15*time.Second).MustWait(ctx, t)
+	d, w := mClock.AdvanceNext()
+	w.MustWait(ctx)
+	require.LessOrEqual(t, d, 15*time.Second)
 	p := testutil.RequireRecvCtx(ctx, t, fPS.pubs)
 	require.Equal(t, pubsub.EventPubsubWatchdog, p)
 	testutil.RequireRecvCtx(ctx, t, uut.Timeout())
diff --git a/enterprise/tailnet/pgcoord.go b/enterprise/tailnet/pgcoord.go
index 857cdafe94e79..104a649d87839 100644
--- a/enterprise/tailnet/pgcoord.go
+++ b/enterprise/tailnet/pgcoord.go
@@ -15,6 +15,7 @@ import (
 	gProto "google.golang.org/protobuf/proto"
 
 	"cdr.dev/slog"
+	"github.com/coder/coder/v2/clock"
 	"github.com/coder/coder/v2/coderd/database"
 	"github.com/coder/coder/v2/coderd/database/dbauthz"
 	"github.com/coder/coder/v2/coderd/database/pubsub"
@@ -115,11 +116,16 @@ var pgCoordSubject = rbac.Subject{
 // NewPGCoord creates a high-availability coordinator that stores state in the PostgreSQL database and
 // receives notifications of updates via the pubsub.
 func NewPGCoord(ctx context.Context, logger slog.Logger, ps pubsub.Pubsub, store database.Store) (agpl.Coordinator, error) {
-	return newPGCoordInternal(ctx, logger, ps, store)
+	return newPGCoordInternal(ctx, logger, ps, store, clock.NewReal())
+}
+
+// NewTestPGCoord is only used in testing to pass a clock.Clock in.
+func NewTestPGCoord(ctx context.Context, logger slog.Logger, ps pubsub.Pubsub, store database.Store, clk clock.Clock) (agpl.Coordinator, error) {
+	return newPGCoordInternal(ctx, logger, ps, store, clk)
 }
 
 func newPGCoordInternal(
-	ctx context.Context, logger slog.Logger, ps pubsub.Pubsub, store database.Store,
+	ctx context.Context, logger slog.Logger, ps pubsub.Pubsub, store database.Store, clk clock.Clock,
 ) (
 	*pgCoord, error,
 ) {
@@ -157,7 +163,7 @@ func newPGCoordInternal(
 		handshaker:       newHandshaker(ctx, logger, id, ps, rfhCh, fHB),
 		handshakerCh:     rfhCh,
 		id:               id,
-		querier:          newQuerier(querierCtx, logger, id, ps, store, id, cCh, ccCh, numQuerierWorkers, fHB),
+		querier:          newQuerier(querierCtx, logger, id, ps, store, id, cCh, ccCh, numQuerierWorkers, fHB, clk),
 		closed:           make(chan struct{}),
 	}
 	go func() {
@@ -817,6 +823,7 @@ func newQuerier(ctx context.Context,
 	closeConnections chan *connIO,
 	numWorkers int,
 	firstHeartbeat chan struct{},
+	clk clock.Clock,
 ) *querier {
 	updates := make(chan hbUpdate)
 	q := &querier{
@@ -828,7 +835,7 @@ func newQuerier(ctx context.Context,
 		newConnections:   newConnections,
 		closeConnections: closeConnections,
 		workQ:            newWorkQ[querierWorkKey](ctx),
-		heartbeats:       newHeartbeats(ctx, logger, ps, store, self, updates, firstHeartbeat),
+		heartbeats:       newHeartbeats(ctx, logger, ps, store, self, updates, firstHeartbeat, clk),
 		mappers:          make(map[mKey]*mapper),
 		updates:          updates,
 		healthy:          true, // assume we start healthy
@@ -1462,12 +1469,12 @@ type heartbeats struct {
 
 	lock         sync.RWMutex
 	coordinators map[uuid.UUID]time.Time
-	timer        *time.Timer
+	timer        *clock.Timer
 
 	wg sync.WaitGroup
 
-	// overwritten in tests, but otherwise constant
-	cleanupPeriod time.Duration
+	// for testing
+	clock clock.Clock
 }
 
 func newHeartbeats(
@@ -1475,6 +1482,7 @@ func newHeartbeats(
 	ps pubsub.Pubsub, store database.Store,
 	self uuid.UUID, update chan<- hbUpdate,
 	firstHeartbeat chan<- struct{},
+	clk clock.Clock,
 ) *heartbeats {
 	h := &heartbeats{
 		ctx:            ctx,
@@ -1485,7 +1493,7 @@ func newHeartbeats(
 		update:         update,
 		firstHeartbeat: firstHeartbeat,
 		coordinators:   make(map[uuid.UUID]time.Time),
-		cleanupPeriod:  cleanupPeriod,
+		clock:          clk,
 	}
 	h.wg.Add(3)
 	go h.subscribe()
@@ -1576,11 +1584,11 @@ func (h *heartbeats) recvBeat(id uuid.UUID) {
 			_ = agpl.SendCtx(h.ctx, h.update, hbUpdate{filter: filterUpdateUpdated})
 		}()
 	}
-	h.coordinators[id] = time.Now()
+	h.coordinators[id] = h.clock.Now("heartbeats", "recvBeat")
 
 	if h.timer == nil {
 		// this can only happen for the very first beat
-		h.timer = time.AfterFunc(MissedHeartbeats*HeartbeatPeriod, h.checkExpiry)
+		h.timer = h.clock.AfterFunc(MissedHeartbeats*HeartbeatPeriod, h.checkExpiry, "heartbeats", "recvBeat")
 		h.logger.Debug(h.ctx, "set initial heartbeat timeout")
 		return
 	}
@@ -1594,24 +1602,30 @@ func (h *heartbeats) resetExpiryTimerWithLock() {
 			oldestTime = t
 		}
 	}
-	d := time.Until(oldestTime.Add(MissedHeartbeats * HeartbeatPeriod))
+	d := h.clock.Until(
+		oldestTime.Add(MissedHeartbeats*HeartbeatPeriod),
+		"heartbeats", "resetExpiryTimerWithLock",
+	)
+	if len(h.coordinators) == 0 {
+		return
+	}
 	h.logger.Debug(h.ctx, "computed oldest heartbeat", slog.F("oldest", oldestTime), slog.F("time_to_expiry", d))
-	// only reschedule if it's in the future.
-	if d > 0 {
-		h.timer.Reset(d)
+	if d < 0 {
+		d = 0
 	}
+	h.timer.Reset(d)
 }
 
 func (h *heartbeats) checkExpiry() {
 	h.logger.Debug(h.ctx, "checking heartbeat expiry")
 	h.lock.Lock()
 	defer h.lock.Unlock()
-	now := time.Now()
+	now := h.clock.Now()
 	expired := false
 	for id, t := range h.coordinators {
 		lastHB := now.Sub(t)
 		h.logger.Debug(h.ctx, "last heartbeat from coordinator", slog.F("other_coordinator_id", id), slog.F("last_heartbeat", lastHB))
-		if lastHB > MissedHeartbeats*HeartbeatPeriod {
+		if lastHB >= MissedHeartbeats*HeartbeatPeriod {
 			expired = true
 			delete(h.coordinators, id)
 			h.logger.Info(h.ctx, "coordinator failed heartbeat check", slog.F("other_coordinator_id", id), slog.F("last_heartbeat", lastHB))
@@ -1633,17 +1647,12 @@ func (h *heartbeats) sendBeats() {
 	h.sendBeat()
 	close(h.firstHeartbeat) // signal binder it can start writing
 	defer h.sendDelete()
-	tkr := time.NewTicker(HeartbeatPeriod)
-	defer tkr.Stop()
-	for {
-		select {
-		case <-h.ctx.Done():
-			h.logger.Debug(h.ctx, "ending heartbeats", slog.Error(h.ctx.Err()))
-			return
-		case <-tkr.C:
-			h.sendBeat()
-		}
-	}
+	tkr := h.clock.TickerFunc(h.ctx, HeartbeatPeriod, func() error {
+		h.sendBeat()
+		return nil
+	}, "heartbeats", "sendBeats")
+	err := tkr.Wait()
+	h.logger.Debug(h.ctx, "ending heartbeats", slog.Error(err))
 }
 
 func (h *heartbeats) sendBeat() {
@@ -1682,17 +1691,12 @@ func (h *heartbeats) sendDelete() {
 func (h *heartbeats) cleanupLoop() {
 	defer h.wg.Done()
 	h.cleanup()
-	tkr := time.NewTicker(h.cleanupPeriod)
-	defer tkr.Stop()
-	for {
-		select {
-		case <-h.ctx.Done():
-			h.logger.Debug(h.ctx, "ending cleanupLoop", slog.Error(h.ctx.Err()))
-			return
-		case <-tkr.C:
-			h.cleanup()
-		}
-	}
+	tkr := h.clock.TickerFunc(h.ctx, cleanupPeriod, func() error {
+		h.cleanup()
+		return nil
+	}, "heartbeats", "cleanupLoop")
+	err := tkr.Wait()
+	h.logger.Debug(h.ctx, "ending cleanupLoop", slog.Error(err))
 }
 
 // cleanup issues a DB command to clean out any old expired coordinators or lost peer state.  The
diff --git a/enterprise/tailnet/pgcoord_internal_test.go b/enterprise/tailnet/pgcoord_internal_test.go
index 4607e6fb2ab2f..5117131c05956 100644
--- a/enterprise/tailnet/pgcoord_internal_test.go
+++ b/enterprise/tailnet/pgcoord_internal_test.go
@@ -10,6 +10,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/coder/coder/v2/clock"
+
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -34,8 +36,7 @@ import (
 // make update-golden-files
 var UpdateGoldenFiles = flag.Bool("update", false, "update .golden files")
 
-// TestHeartbeats_Cleanup is internal so that we can overwrite the cleanup period and not wait an hour for the timed
-// cleanup.
+// TestHeartbeats_Cleanup tests the cleanup loop
 func TestHeartbeats_Cleanup(t *testing.T) {
 	t.Parallel()
 
@@ -46,38 +47,82 @@ func TestHeartbeats_Cleanup(t *testing.T) {
 	defer cancel()
 	logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
 
-	waitForCleanup := make(chan struct{})
-	mStore.EXPECT().CleanTailnetCoordinators(gomock.Any()).MinTimes(2).DoAndReturn(func(_ context.Context) error {
-		<-waitForCleanup
-		return nil
-	})
-	mStore.EXPECT().CleanTailnetLostPeers(gomock.Any()).MinTimes(2).DoAndReturn(func(_ context.Context) error {
-		<-waitForCleanup
-		return nil
-	})
-	mStore.EXPECT().CleanTailnetTunnels(gomock.Any()).MinTimes(2).DoAndReturn(func(_ context.Context) error {
-		<-waitForCleanup
-		return nil
-	})
+	mStore.EXPECT().CleanTailnetCoordinators(gomock.Any()).Times(2).Return(nil)
+	mStore.EXPECT().CleanTailnetLostPeers(gomock.Any()).Times(2).Return(nil)
+	mStore.EXPECT().CleanTailnetTunnels(gomock.Any()).Times(2).Return(nil)
+
+	mClock := clock.NewMock(t)
+	trap := mClock.Trap().TickerFunc("heartbeats", "cleanupLoop")
+	defer trap.Close()
 
 	uut := &heartbeats{
-		ctx:           ctx,
-		logger:        logger,
-		store:         mStore,
-		cleanupPeriod: time.Millisecond,
+		ctx:    ctx,
+		logger: logger,
+		store:  mStore,
+		clock:  mClock,
 	}
 	uut.wg.Add(1)
 	go uut.cleanupLoop()
 
-	for i := 0; i < 6; i++ {
-		select {
-		case <-ctx.Done():
-			t.Fatal("timeout")
-		case waitForCleanup <- struct{}{}:
-			// ok
-		}
+	call, err := trap.Wait(ctx)
+	require.NoError(t, err)
+	call.Release()
+	require.Equal(t, cleanupPeriod, call.Duration)
+	mClock.Advance(cleanupPeriod).MustWait(ctx)
+}
+
+// TestHeartbeats_recvBeat_resetSkew is a regression test for a bug where heartbeats from two
+// coordinators slightly skewed from one another could result in one coordinator failing to get
+// expired
+func TestHeartbeats_recvBeat_resetSkew(t *testing.T) {
+	t.Parallel()
+
+	ctx := testutil.Context(t, testutil.WaitShort)
+	logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
+	mClock := clock.NewMock(t)
+	trap := mClock.Trap().Until("heartbeats", "resetExpiryTimerWithLock")
+	defer trap.Close()
+
+	uut := heartbeats{
+		ctx:          ctx,
+		logger:       logger,
+		clock:        mClock,
+		self:         uuid.UUID{1},
+		update:       make(chan hbUpdate, 4),
+		coordinators: make(map[uuid.UUID]time.Time),
 	}
-	close(waitForCleanup)
+
+	coord2 := uuid.UUID{2}
+	coord3 := uuid.UUID{3}
+
+	uut.listen(ctx, []byte(coord2.String()), nil)
+
+	// coord 3 heartbeat comes very soon after
+	mClock.Advance(time.Millisecond).MustWait(ctx)
+	go uut.listen(ctx, []byte(coord3.String()), nil)
+	trap.MustWait(ctx).Release()
+
+	// both coordinators are present
+	uut.lock.RLock()
+	require.Contains(t, uut.coordinators, coord2)
+	require.Contains(t, uut.coordinators, coord3)
+	uut.lock.RUnlock()
+
+	// no more heartbeats arrive, and coord2 expires
+	w := mClock.Advance(MissedHeartbeats*HeartbeatPeriod - time.Millisecond)
+	// however, several ms pass between expiring 2 and computing the time until 3 expires
+	c := trap.MustWait(ctx)
+	mClock.Advance(2 * time.Millisecond).MustWait(ctx) // 3 has now expired _in the past_
+	c.Release()
+	w.MustWait(ctx)
+
+	// expired in the past means we immediately reschedule checkExpiry, so we get another call
+	trap.MustWait(ctx).Release()
+
+	uut.lock.RLock()
+	require.NotContains(t, uut.coordinators, coord2)
+	require.NotContains(t, uut.coordinators, coord3)
+	uut.lock.RUnlock()
 }
 
 func TestHeartbeats_LostCoordinator_MarkLost(t *testing.T) {
@@ -85,25 +130,26 @@ func TestHeartbeats_LostCoordinator_MarkLost(t *testing.T) {
 
 	ctrl := gomock.NewController(t)
 	mStore := dbmock.NewMockStore(ctrl)
+	mClock := clock.NewMock(t)
 
 	ctx, cancel := context.WithTimeout(context.Background(), testutil.WaitShort)
 	defer cancel()
 	logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
 
 	uut := &heartbeats{
-		ctx:           ctx,
-		logger:        logger,
-		store:         mStore,
-		cleanupPeriod: time.Millisecond,
+		ctx:    ctx,
+		logger: logger,
+		store:  mStore,
 		coordinators: map[uuid.UUID]time.Time{
-			uuid.New(): time.Now(),
+			uuid.New(): mClock.Now(),
 		},
+		clock: mClock,
 	}
 
 	mpngs := []mapping{{
 		peer:        uuid.New(),
 		coordinator: uuid.New(),
-		updatedAt:   time.Now(),
+		updatedAt:   mClock.Now(),
 		node:        &proto.Node{},
 		kind:        proto.CoordinateResponse_PeerUpdate_NODE,
 	}}
@@ -342,11 +388,14 @@ func TestPGCoordinatorUnhealthy(t *testing.T) {
 	ctrl := gomock.NewController(t)
 	mStore := dbmock.NewMockStore(ctrl)
 	ps := pubsub.NewInMemory()
+	mClock := clock.NewMock(t)
+	tfTrap := mClock.Trap().TickerFunc("heartbeats", "sendBeats")
+	defer tfTrap.Close()
 
 	// after 3 failed heartbeats, the coordinator is unhealthy
 	mStore.EXPECT().
 		UpsertTailnetCoordinator(gomock.Any(), gomock.Any()).
-		MinTimes(3).
+		Times(3).
 		Return(database.TailnetCoordinator{}, xerrors.New("badness"))
 	mStore.EXPECT().
 		DeleteCoordinator(gomock.Any(), gomock.Any()).
@@ -360,9 +409,22 @@ func TestPGCoordinatorUnhealthy(t *testing.T) {
 	mStore.EXPECT().CleanTailnetLostPeers(gomock.Any()).AnyTimes().Return(nil)
 	mStore.EXPECT().CleanTailnetTunnels(gomock.Any()).AnyTimes().Return(nil)
 
-	coordinator, err := newPGCoordInternal(ctx, logger, ps, mStore)
+	coordinator, err := newPGCoordInternal(ctx, logger, ps, mStore, mClock)
+	require.NoError(t, err)
+
+	expectedPeriod := HeartbeatPeriod
+	tfCall, err := tfTrap.Wait(ctx)
 	require.NoError(t, err)
+	tfCall.Release()
+	require.Equal(t, expectedPeriod, tfCall.Duration)
+
+	// Now that the ticker has started, we can advance 2 more beats to get to 3
+	// failed heartbeats
+	mClock.Advance(HeartbeatPeriod).MustWait(ctx)
+	mClock.Advance(HeartbeatPeriod).MustWait(ctx)
 
+	// The querier is informed async about being unhealthy, so we need to wait
+	// until it is.
 	require.Eventually(t, func() bool {
 		return !coordinator.querier.isHealthy()
 	}, testutil.WaitShort, testutil.IntervalFast)
diff --git a/enterprise/tailnet/pgcoord_test.go b/enterprise/tailnet/pgcoord_test.go
index 9c363ee700570..c02774adb7245 100644
--- a/enterprise/tailnet/pgcoord_test.go
+++ b/enterprise/tailnet/pgcoord_test.go
@@ -10,6 +10,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/coder/coder/v2/clock"
+
 	"github.com/google/uuid"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -337,7 +339,13 @@ func TestPGCoordinatorSingle_MissedHeartbeats(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), testutil.WaitSuperLong)
 	defer cancel()
 	logger := slogtest.Make(t, nil).Leveled(slog.LevelDebug)
-	coordinator, err := tailnet.NewPGCoord(ctx, logger, ps, store)
+	mClock := clock.NewMock(t)
+	nowTrap := mClock.Trap().Now("heartbeats", "recvBeat")
+	defer nowTrap.Close()
+	afTrap := mClock.Trap().AfterFunc("heartbeats", "recvBeat")
+	defer afTrap.Close()
+
+	coordinator, err := tailnet.NewTestPGCoord(ctx, logger, ps, store, mClock)
 	require.NoError(t, err)
 	defer coordinator.Close()
 
@@ -360,21 +368,11 @@ func TestPGCoordinatorSingle_MissedHeartbeats(t *testing.T) {
 		store: store,
 		id:    uuid.New(),
 	}
-	// heatbeat until canceled
-	ctx2, cancel2 := context.WithCancel(ctx)
-	go func() {
-		t := time.NewTicker(tailnet.HeartbeatPeriod)
-		defer t.Stop()
-		for {
-			select {
-			case <-ctx2.Done():
-				return
-			case <-t.C:
-				fCoord2.heartbeat()
-			}
-		}
-	}()
+
 	fCoord2.heartbeat()
+	nowTrap.MustWait(ctx).Release()
+	afTrap.MustWait(ctx).Release() // heartbeat timeout started
+
 	fCoord2.agentNode(agent.id, &agpl.Node{PreferredDERP: 12})
 	assertEventuallyHasDERPs(ctx, t, client, 12)
 
@@ -384,22 +382,31 @@ func TestPGCoordinatorSingle_MissedHeartbeats(t *testing.T) {
 		store: store,
 		id:    uuid.New(),
 	}
-	start := time.Now()
 	fCoord3.heartbeat()
+	nowTrap.MustWait(ctx).Release()
 	fCoord3.agentNode(agent.id, &agpl.Node{PreferredDERP: 13})
 	assertEventuallyHasDERPs(ctx, t, client, 13)
 
+	// fCoord2 sends in a second heartbeat, one period later (on time)
+	fCoord2.heartbeat()
+	c := nowTrap.MustWait(ctx)
+	mClock.Advance(tailnet.HeartbeatPeriod).MustWait(ctx)
+	c.Release()
+
 	// when the fCoord3 misses enough heartbeats, the real coordinator should send an update with the
 	// node from fCoord2 for the agent.
+	mClock.Advance(tailnet.HeartbeatPeriod).MustWait(ctx)
+	mClock.Advance(tailnet.HeartbeatPeriod).MustWait(ctx)
 	assertEventuallyHasDERPs(ctx, t, client, 12)
-	assert.Greater(t, time.Since(start), tailnet.HeartbeatPeriod*tailnet.MissedHeartbeats)
 
-	// stop fCoord2 heartbeats, which should cause us to revert to the original agent mapping
-	cancel2()
+	// one more heartbeat period will result in fCoord2 being expired, which should cause us to
+	// revert to the original agent mapping
+	mClock.Advance(tailnet.HeartbeatPeriod).MustWait(ctx)
 	assertEventuallyHasDERPs(ctx, t, client, 10)
 
 	// send fCoord3 heartbeat, which should trigger us to consider that mapping valid again.
 	fCoord3.heartbeat()
+	nowTrap.MustWait(ctx).Release()
 	assertEventuallyHasDERPs(ctx, t, client, 13)
 
 	err = agent.close()
diff --git a/tailnet/configmaps_internal_test.go b/tailnet/configmaps_internal_test.go
index c658e5fb2f44e..83b15387a9a43 100644
--- a/tailnet/configmaps_internal_test.go
+++ b/tailnet/configmaps_internal_test.go
@@ -195,7 +195,7 @@ func TestConfigMaps_updatePeers_new_waitForHandshake_neverConfigures(t *testing.
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	uut.clock = mClock
 
 	p1ID := uuid.UUID{1}
@@ -239,7 +239,7 @@ func TestConfigMaps_updatePeers_new_waitForHandshake_outOfOrder(t *testing.T) {
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	uut.clock = mClock
 
 	p1ID := uuid.UUID{1}
@@ -310,7 +310,7 @@ func TestConfigMaps_updatePeers_new_waitForHandshake(t *testing.T) {
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	uut.clock = mClock
 
 	p1ID := uuid.UUID{1}
@@ -381,7 +381,7 @@ func TestConfigMaps_updatePeers_new_waitForHandshake_timeout(t *testing.T) {
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	uut.clock = mClock
 
 	p1ID := uuid.UUID{1}
@@ -404,7 +404,7 @@ func TestConfigMaps_updatePeers_new_waitForHandshake_timeout(t *testing.T) {
 	}
 	uut.updatePeers(u1)
 
-	mClock.Advance(5*time.Second).MustWait(ctx, t)
+	mClock.Advance(5 * time.Second).MustWait(ctx)
 
 	// it should now send the peer to the netmap
 
@@ -566,7 +566,7 @@ func TestConfigMaps_updatePeers_lost(t *testing.T) {
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	start := mClock.Now()
 	uut.clock = mClock
 
@@ -591,7 +591,7 @@ func TestConfigMaps_updatePeers_lost(t *testing.T) {
 	require.Len(t, r.wg.Peers, 1)
 	_ = testutil.RequireRecvCtx(ctx, t, s1)
 
-	mClock.Advance(5*time.Second).MustWait(ctx, t)
+	mClock.Advance(5 * time.Second).MustWait(ctx)
 
 	s2 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, start)
 
@@ -612,7 +612,8 @@ func TestConfigMaps_updatePeers_lost(t *testing.T) {
 	// latest handshake has advanced by a minute, so we don't remove the peer.
 	lh := start.Add(time.Minute)
 	s3 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, lh)
-	mClock.Advance(lostTimeout).MustWait(ctx, t)
+	// 5 seconds have already elapsed from above
+	mClock.Advance(lostTimeout - 5*time.Second).MustWait(ctx)
 	_ = testutil.RequireRecvCtx(ctx, t, s3)
 	select {
 	case <-fEng.setNetworkMap:
@@ -624,7 +625,7 @@ func TestConfigMaps_updatePeers_lost(t *testing.T) {
 	// Advance the clock again by a minute, which should trigger the reprogrammed
 	// timeout.
 	s4 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, lh)
-	mClock.Advance(time.Minute).MustWait(ctx, t)
+	mClock.Advance(time.Minute).MustWait(ctx)
 
 	nm = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)
 	r = testutil.RequireRecvCtx(ctx, t, fEng.reconfig)
@@ -650,7 +651,7 @@ func TestConfigMaps_updatePeers_lost_and_found(t *testing.T) {
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	start := mClock.Now()
 	uut.clock = mClock
 
@@ -675,7 +676,7 @@ func TestConfigMaps_updatePeers_lost_and_found(t *testing.T) {
 	require.Len(t, r.wg.Peers, 1)
 	_ = testutil.RequireRecvCtx(ctx, t, s1)
 
-	mClock.Advance(5*time.Second).MustWait(ctx, t)
+	mClock.Advance(5 * time.Second).MustWait(ctx)
 
 	s2 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, start)
 
@@ -692,7 +693,7 @@ func TestConfigMaps_updatePeers_lost_and_found(t *testing.T) {
 		// OK!
 	}
 
-	mClock.Advance(5*time.Second).MustWait(ctx, t)
+	mClock.Advance(5 * time.Second).MustWait(ctx)
 	s3 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, start)
 
 	updates[0].Kind = proto.CoordinateResponse_PeerUpdate_NODE
@@ -709,7 +710,7 @@ func TestConfigMaps_updatePeers_lost_and_found(t *testing.T) {
 
 	// When we advance the clock, nothing happens because the timeout was
 	// canceled
-	mClock.Advance(lostTimeout).MustWait(ctx, t)
+	mClock.Advance(lostTimeout).MustWait(ctx)
 	select {
 	case <-fEng.setNetworkMap:
 		t.Fatal("should not reprogram")
@@ -735,7 +736,7 @@ func TestConfigMaps_setAllPeersLost(t *testing.T) {
 	discoKey := key.NewDisco()
 	uut := newConfigMaps(logger, fEng, nodeID, nodePrivateKey, discoKey.Public())
 	defer uut.close()
-	mClock := clock.NewMock()
+	mClock := clock.NewMock(t)
 	start := mClock.Now()
 	uut.clock = mClock
 
@@ -769,7 +770,7 @@ func TestConfigMaps_setAllPeersLost(t *testing.T) {
 	require.Len(t, r.wg.Peers, 2)
 	_ = testutil.RequireRecvCtx(ctx, t, s1)
 
-	mClock.Advance(5*time.Second).MustWait(ctx, t)
+	mClock.Advance(5 * time.Second).MustWait(ctx)
 	uut.setAllPeersLost()
 
 	// No reprogramming yet, since we keep the peer around.
@@ -780,10 +781,12 @@ func TestConfigMaps_setAllPeersLost(t *testing.T) {
 		// OK!
 	}
 
-	// When we advance the clock, even by a few ms, the timeout for peer 2 pops
-	// because our status only includes a handshake for peer 1
+	// When we advance the clock, even by a millisecond, the timeout for peer 2
+	// pops because our status only includes a handshake for peer 1
 	s2 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, start)
-	mClock.Advance(time.Millisecond*10).MustWait(ctx, t)
+	d, w := mClock.AdvanceNext()
+	w.MustWait(ctx)
+	require.LessOrEqual(t, d, time.Millisecond)
 	_ = testutil.RequireRecvCtx(ctx, t, s2)
 
 	nm = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)
@@ -793,7 +796,7 @@ func TestConfigMaps_setAllPeersLost(t *testing.T) {
 
 	// Finally, advance the clock until after the timeout
 	s3 := expectStatusWithHandshake(ctx, t, fEng, p1Node.Key, start)
-	mClock.Advance(lostTimeout).MustWait(ctx, t)
+	mClock.Advance(lostTimeout - d - 5*time.Second).MustWait(ctx)
 	_ = testutil.RequireRecvCtx(ctx, t, s3)
 
 	nm = testutil.RequireRecvCtx(ctx, t, fEng.setNetworkMap)