test(tools_test.go/Test_CheckRules_Glob): take into consideration RO …

…current dirs while

changing files permissions.

The process may not have the needed permissions on the file (not the owner, not root or doesn't have the CAP_FOWNER capability)
to chmod it.

Signed-off-by: machine424 <[email protected]>

cmd/thanos/tools_test.go

@@ -5,6 +5,7 @@ package main
 
 import (
 	"os"
+	"path"
 	"testing"
 
 	"github.com/go-kit/log"
@@ -47,9 +48,12 @@ func Test_CheckRules_Glob(t *testing.T) {
 	testutil.NotOk(t, checkRulesFiles(logger, files), "expected err for file %s", files)
 
 	// Unreadble path
-	files = &[]string{"./testdata/rules-files/unreadable_valid.yaml"}
-	filename := (*files)[0]
-	testutil.Ok(t, os.Chmod(filename, 0000), "failed to change file permissions of %s to 0000", filename)
+	// Move the initial file to a temp dir and make it inaccessible there, in case the current dir is RO.
+	filename := "./testdata/rules-files/unreadable_valid.yaml"
+	bytesRead, err := os.ReadFile(filename)
+	testutil.Ok(t, err)
+	filename = path.Join(t.TempDir(), "file.yaml")
+	testutil.Ok(t, os.WriteFile(filename, bytesRead, 0000))
+	files = &[]string{filename}
 	testutil.NotOk(t, checkRulesFiles(logger, files), "expected err for file %s", files)
-	testutil.Ok(t, os.Chmod(filename, 0777), "failed to change file permissions of %s to 0777", filename)
 }