Implement app update orchestration (T-402)

app-modern/platform/windows/platform_test.go

@@ -1,9 +1,11 @@
 package windows
 
 import (
+	"context"
 	"errors"
 	"path/filepath"
 	"testing"
+	"time"
 )
 
 func TestPlatformStubContract(t *testing.T) {
@@ -78,6 +80,71 @@ func TestVersionSupports(t *testing.T) {
 	}
 }
 
+func TestWaitForExit(t *testing.T) {
+	initial := time.Date(2026, 7, 19, 0, 0, 0, 0, time.UTC)
+	errSnapshot := errors.New("snapshot failed")
+	tests := []struct {
+		name       string
+		ctx        context.Context
+		running    []bool
+		runErr     error
+		timeout    time.Duration
+		wantErr    error
+		wantSleeps int
+	}{
+		{name: "already stopped", ctx: context.Background(), running: []bool{false}, timeout: time.Second},
+		{name: "stops after one poll", ctx: context.Background(), running: []bool{true, false}, timeout: time.Second, wantSleeps: 1},
+		{name: "timeout", ctx: context.Background(), running: []bool{true, true, true, true, true}, timeout: time.Second, wantErr: context.DeadlineExceeded, wantSleeps: 4},
+		{name: "snapshot failure", ctx: context.Background(), runErr: errSnapshot, timeout: time.Second, wantErr: errSnapshot},
+		{name: "canceled", ctx: canceledWaitContext(), running: []bool{true}, timeout: time.Second, wantErr: context.Canceled},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			clock := &fakeExitWaitClock{now: initial}
+			index := 0
+			err := waitForExit(test.ctx, test.timeout, func() (bool, error) {
+				if test.runErr != nil {
+					return false, test.runErr
+				}
+				if index >= len(test.running) {
+					return test.running[len(test.running)-1], nil
+				}
+				running := test.running[index]
+				index++
+				return running, nil
+			}, clock)
+			if !errors.Is(err, test.wantErr) {
+				t.Fatalf("waitForExit() error = %v, want %v", err, test.wantErr)
+			}
+			if clock.sleeps != test.wantSleeps {
+				t.Fatalf("sleeps = %d, want %d", clock.sleeps, test.wantSleeps)
+			}
+		})
+	}
+}
+
+func canceledWaitContext() context.Context {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	return ctx
+}
+
+type fakeExitWaitClock struct {
+	now    time.Time
+	sleeps int
+}
+
+func (clock *fakeExitWaitClock) Now() time.Time { return clock.now }
+
+func (clock *fakeExitWaitClock) Wait(ctx context.Context, duration time.Duration) error {
+	if err := ctx.Err(); err != nil {
+		return err
+	}
+	clock.sleeps++
+	clock.now = clock.now.Add(duration)
+	return nil
+}
+
 type snapshotItem struct {
 	path string
 	err  error