Remove TestExchangedata* tests for old macOS

The exchangedata() system call has never been supported on APFS
introduced in macOS 10.13 (2017, unsupported since late 2020) and since
macOS 10.14 (2018, unsupported since mid 2021) all HFS+ drives are
converted to APFS. As far as I can find you can't use HFS+ drives with
current versions of macOS:

https://old.reddit.com/r/macsysadmin/comments/tk5lsi/use_hfs_instead_of_apfs_with_monterey/
https://old.reddit.com/r/MacOS/comments/jgodi9/i_cannot_update_because_i_cannot_convert_to_apfs/

So it seems we can safely remove this test. It wasn't run in the CI
anyway, as this only tests macOS 11 and 12.

diff --git a/system_darwin_test.go b/system_darwin_test.go
deleted file mode 100644 (file)
index 75fdb65..0000000
--- a/system_darwin_test.go
+++ /dev/null
@@ -1,122 +0,0 @@
-//go:build darwin
-// +build darwin
-
-package fsnotify
-
-import (
-       "os"
-       "strconv"
-       "strings"
-       "testing"
-
-       "golang.org/x/sys/unix"
-)
-
-// darwinVersion returns version os Darwin (17 is macOS 10.13).
-func darwinVersion() (int, error) {
-       s, err := unix.Sysctl("kern.osrelease")
-       if err != nil {
-               return 0, err
-       }
-       s = strings.Split(s, ".")[0]
-       return strconv.Atoi(s)
-}
-
-// testExchangedataForWatcher tests the watcher with the exchangedata operation
-// on macOS. This is widely used for atomic saves on macOS, e.g. TextMate and in
-// Apple's NSDocument.
-//
-// https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man2/exchangedata.2.html
-// https://github.com/textmate/textmate/blob/cd016be2/Frameworks/io/src/swap_file_data.cc#L20
-func testExchangedataForWatcher(t *testing.T, watchDir bool) {
-       osVersion, err := darwinVersion()
-       if err != nil {
-               t.Fatal("unable to get Darwin version:", err)
-       }
-       if osVersion >= 17 {
-               t.Skip("Exchangedata is deprecated in macOS 10.13")
-       }
-
-       testDir1 := t.TempDir() // Create directory to watch
-       testDir2 := t.TempDir() // For the intermediate file
-
-       resolvedFilename := "TestFsnotifyEvents.file"
-
-       // TextMate does:
-       //
-       // 1. exchangedata (intermediate, resolved)
-       // 2. unlink intermediate
-       //
-       // Let's try to simulate that:
-       resolved := join(testDir1, resolvedFilename)
-       intermediate := join(testDir2, resolvedFilename+"~")
-
-       // Make sure we create the file before we start watching
-       createAndSyncFile(t, resolved)
-
-       w := newCollector(t)
-       w.collect(t)
-
-       // Test both variants in isolation
-       if watchDir {
-               addWatch(t, w.w, testDir1)
-       } else {
-               addWatch(t, w.w, resolved)
-       }
-
-       // Repeat to make sure the watched file/directory "survives" the
-       // REMOVE/CREATE loop.
-       for i := 1; i <= 3; i++ {
-               createAndSyncFile(t, intermediate) // intermediate file is created outside the watcher
-
-               if err := unix.Exchangedata(intermediate, resolved, 0); err != nil { // 1. Swap
-                       t.Fatalf("[%d] exchangedata failed: %s", i, err)
-               }
-               eventSeparator()
-               err := os.Remove(intermediate) // delete the intermediate file
-               if err != nil {
-                       t.Fatalf("[%d] remove %s failed: %s", i, intermediate, err)
-               }
-
-               eventSeparator()
-       }
-
-       // The events will be (CHMOD + REMOVE + CREATE) X 2. Let's focus on the last two:
-       events := w.stop(t)
-       var rm, create Events
-       for _, e := range events {
-               if e.Has(Create) {
-                       create = append(create, e)
-               }
-               if e.Has(Remove) {
-                       rm = append(rm, e)
-               }
-       }
-       if len(rm) < 3 {
-               t.Fatalf("less than 3 REMOVE events:\n%s", events)
-       }
-       if len(create) < 3 {
-               t.Fatalf("less than 3 CREATE events:\n%s", events)
-       }
-}
-
-func createAndSyncFile(t *testing.T, filepath string) {
-       f1, err := os.OpenFile(filepath, os.O_WRONLY|os.O_CREATE, 0666)
-       if err != nil {
-               t.Fatalf("creating %s failed: %s", filepath, err)
-       }
-       f1.Sync()
-       f1.Close()
-}
-
-// TestExchangedataInWatchedDir test exchangedata operation on file in watched dir.
-func TestExchangedataInWatchedDir(t *testing.T) {
-       t.Parallel()
-       testExchangedataForWatcher(t, true)
-}
-
-// TestExchangedataInWatchedDir test exchangedata operation on watched file.
-func TestExchangedataInWatchedFile(t *testing.T) {
-       t.Parallel()
-       testExchangedataForWatcher(t, false)
-}