go/zodb/zeo: Test it on all py2/py3 ZODB kinds of data we care about and wrt...

go/zodb/zeo: Test it on all py2/py3 ZODB kinds of data we care about and wrt both ZEO/py2 and ZEO/py3

Similarly to FileStorage, fs1tools and other Go packages previously we
were testing ZEO/go client only with old FileStorage testdata generated
by python2 and pickle protocol=2. However even on py2 there are more
pickle protocols that are in use, and also there is python3.

We were also testing our ZEO/go client only wrt ZEO/py2 but there is
also ZEO/py3.

-> Adjust ZEO/go testing to automatically load and test against all ZODB
kinds from recently updated FileStorage testdata and wrt both ZEO/py2
and ZEO/py3.

All py2_pickle1, py2_pickle2, py2_pickle3 and py3_pickle3 are handled well out of the box.
However only ZEO/py2 succeeds: tests wrt ZEO/py3 server currently fail
and so are marked with "xfail".

We will fix tests for ZEO/py3 in the next patch.

go/zodb/storage/zeo/zeo_test.go

-// Copyright (C) 2020  Nexedi SA and Contributors.
+// Copyright (C) 2020-2024  Nexedi SA and Contributors.
 //                          Kirill Smelkov <kirr@nexedi.com>
 //
 // This program is free software: you can Use, Study, Modify and Redistribute
@@ -26,13 +26,14 @@ import (
 	"net/url"
 	"os"
 	"os/exec"
+	"strings"
 	"testing"
 	"time"
 
 	"lab.nexedi.com/kirr/neo/go/internal/xexec"
 	"lab.nexedi.com/kirr/neo/go/internal/xtesting"
 	"lab.nexedi.com/kirr/neo/go/zodb"
-	_ "lab.nexedi.com/kirr/neo/go/zodb/storage/fs1"
+	"lab.nexedi.com/kirr/neo/go/zodb/storage/fs1"
 
 	"lab.nexedi.com/kirr/go123/xerr"
 	"lab.nexedi.com/kirr/go123/xnet"
@@ -187,8 +188,9 @@ func withZEOSrv(t *testing.T, f func(t *testing.T, zsrv ZEOSrv), optv ...tOption
 	}
 
 	for _, msgpack := range []bool{false, true} {
+		t.Run(fmt.Sprintf("msgpack=%v", msgpack), func(t *testing.T) {
 			// ZEO/py
-		t.Run(fmt.Sprintf("py/msgpack=%v", msgpack), func(t *testing.T) {
+			xtesting.WithEachPy(t, func(t *testing.T) {
 				t.Helper()
 				needpy := []string{"ZEO"}
 				if msgpack {
@@ -196,9 +198,24 @@ func withZEOSrv(t *testing.T, f func(t *testing.T, zsrv ZEOSrv), optv ...tOption
 					needpy = append(needpy, "ZEO.asyncio") // FIXME hack to check that ZEO ver >= 5
 				}
 				xtesting.NeedPy(t, needpy...)
+				py2 := strings.HasSuffix(t.Name(), "/py2")
+				if !msgpack && !py2 {
+					t.Skip("xfail")
+				}
 				withFS1(t, func(fs1path string) {
 					X := xtesting.FatalIf(t)
 
+					// adjust FileStorage magic to match current python because FileStorage/py
+					// rejects to open data created under different major version of python
+					if opt.Preload != "" {
+						magic := fs1.Magic30
+						if py2 {
+							magic = fs1.Magic21
+						}
+						fs1, err := os.OpenFile(fs1path, os.O_RDWR, 0); X(err)
+						_, err = fs1.WriteAt([]byte(magic), 0); X(err)
+					}
+
 					zpy, err := StartZEOPySrv(fs1path, ZEOPyOptions{msgpack: msgpack}); X(err)
 					defer func() {
 						err := zpy.Close(); X(err)
@@ -207,6 +224,7 @@ func withZEOSrv(t *testing.T, f func(t *testing.T, zsrv ZEOSrv), optv ...tOption
 					f(t, zpy)
 				})
 			})
+		})
 	}
 }
 
@@ -252,10 +270,22 @@ func TestEmptyDB(t *testing.T) {
 	})
 }
 
+
+// ztestdataReg keeps registry of ZODB test data we use in tests with non-empty Preload.
+// we take the data from fs1 testdata.
+var  ztestdataReg = xtesting.ZTestDataRegistry[struct{}]{}
+type ZTestData    = xtesting.ZTestData[struct{}]
+func init() {
+	ztestdataReg = xtesting.LoadZTestData("../fs1/testdata")
+}
+
 func TestLoad(t *testing.T) {
+	ztestdataReg.RunWithEach(t, _TestLoad)
+}
+func _TestLoad(t *testing.T, z *ZTestData) {
 	X := xtesting.FatalIf(t)
 
-	data := "../fs1/testdata/1.fs"
+	data := z.Path("1.fs")
 	txnvOk, err := xtesting.LoadDBHistory(data); X(err)
 
 	withZEO(t, func(t *testing.T, zsrv ZEOSrv, z *zeo) {