fix tests for Windows

Author: chlowell

extensions/cache/cache_test.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"runtime"
 	"sync"
 	"testing"
 	"time"
@@ -93,6 +94,7 @@ func TestExport(t *testing.T) {
 
 	// Export should write the in-memory cache to the accessor and touch the timestamp file
 	lastWrite := time.Time{}
+	touched := false
 	for i := 0; i < 3; i++ {
 		s := fmt.Sprint(i)
 		*ic = fakeInternalCache{data: []byte(s)}
@@ -103,9 +105,19 @@ func TestExport(t *testing.T) {
 		f, err := os.Stat(p)
 		require.NoError(t, err)
 		mt := f.ModTime()
-		require.NotEqual(t, lastWrite, mt, "Export should have updated the timestamp")
+
+		// Two iterations of this loop can run within one unit of system time on Windows, leaving the
+		// modtime apparently unchanged even though Export updated it. On Windows we therefore skip
+		// the strict test, instead requiring only that the modtime change once during this loop.
+		if runtime.GOOS != "windows" {
+			require.NotEqual(t, lastWrite, mt, "Export didn't update the timestamp")
+		}
+		if mt != lastWrite {
+			touched = true
+		}
 		lastWrite = mt
 	}
+	require.True(t, touched, "Export didn't update the timestamp")
 }
 
 func TestFilenameCompat(t *testing.T) {
@@ -189,8 +201,9 @@ func TestReplace(t *testing.T) {
 	require.Empty(t, ic)
 
 	// Replace should read data from the accessor (external cache) into the in-memory cache, observing the timestamp file
-	_, err = os.Create(p)
+	f, err := os.Create(p)
 	require.NoError(t, err)
+	require.NoError(t, f.Close())
 	for i := uint8(0); i < 4; i++ {
 		ec.data = []byte{i}
 		err = c.Replace(ctx, &ic, cache.ReplaceHints{})