Revert "plugin/sign: track zone file's mtime (#4431)" (#4511)

This reverts commit c4720b8ad2.

plugin/sign/resign_test.go

@@ -1,12 +1,9 @@
 package sign
 
 import (
-	"os"
 	"strings"
 	"testing"
 	"time"
-
-	"github.com/coredns/caddy"
 )
 
 func TestResignInception(t *testing.T) {
@@ -41,52 +38,3 @@ func TestResignExpire(t *testing.T) {
 		t.Errorf("Expected RRSIG to be invalid for %s, got valid", then.Format(timeFmt))
 	}
 }
-
-func TestResignModTime(t *testing.T) {
-	input := `sign testdata/db.miek.nl miek.nl {
-               key file testdata/Kmiek.nl.+013+59725
-               directory testdata
-       }`
-	c := caddy.NewTestController("dns", input)
-	sign, err := parse(c)
-	if err != nil {
-		t.Fatal(err)
-	}
-	defer os.Remove("testdata/db.miek.nl.signed")
-
-	if len(sign.signers) != 1 {
-		t.Fatalf("Expected 1 signer, got %d", len(sign.signers))
-	}
-	signer := sign.signers[0]
-
-	why := signer.resign()
-	if !strings.Contains(why.Error(), "no such file or directory") {
-		t.Fatalf("Expected %q, got: %s", "no such file or directory", why.Error())
-	}
-
-	// Slightly harder to properly test this, as we need to pull in the zone writing as well.
-	z, err := signer.Sign(time.Now().UTC())
-	if err != nil {
-		t.Fatal(err)
-	}
-	if err := signer.write(z); err != nil {
-		t.Fatal(err)
-	}
-	if x := signer.modTime; x.IsZero() {
-		t.Errorf("Expected non zero modification time: got: %s", x.Format(timeFmt))
-	}
-
-	why = signer.resign()
-	if why != nil {
-		t.Errorf("Expected not to have to resign the zone, got: %s", why)
-	}
-
-	// set mtime on original zone file and see if we pick it up as a cue to resign
-	if err := os.Chtimes("testdata/db.miek.nl", time.Now(), time.Now()); err != nil {
-		t.Fatal(err)
-	}
-	why = signer.resign()
-	if !strings.Contains(why.Error(), "differs from last seen modification") {
-		t.Errorf("Expecting to resign the zone, but got: %s", why.Error())
-	}
-}