test(windows): redirect now/nowTime to time.Now() in tests

On Windows, var now points to GetSystemTimePreciseAsFileTime() via a
direct Windows syscall. This syscall bypasses testing/synctest's fake
clock, which only intercepts time.Now(). As a result, synctest-wrapped
tests fail on Windows: span durations read the real wall clock (a few
µs) instead of the fake 2 ms advance, and span-age strings diverge
between the test and the code under test.

Add an init() in time_windows_test.go that overrides now and nowTime to
call time.Now() for the test binary. Production code keeps its
high-precision syscall; tests gain fake-clock compatibility without any
change to production behavior.

Signed-off-by: Kemal Akkoyun <kemal.akkoyun@datadoghq.com>

Author: kakkoyun

ddtrace/tracer/time_windows_test.go

@@ -7,10 +7,21 @@ package tracer
 
 import (
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 )
 
+func init() {
+	// Override now and nowTime to use time.Now() in tests. Production code
+	// calls GetSystemTimePreciseAsFileTime() directly for higher precision, but
+	// that syscall bypasses testing/synctest's fake clock. time.Now() is
+	// intercepted by synctest, so this makes the fake clock work correctly on
+	// Windows without changing production behavior.
+	now = func() int64 { return time.Now().UnixNano() }
+	nowTime = func() time.Time { return time.Now() }
+}
+
 func BenchmarkNormalTimeNow(b *testing.B) {
 	for n := 0; n < b.N; n++ {
 		lowPrecisionNow()