fixup! client_test: Support test cluster /w >1 master

- show all options in error context and ran test kind

- skip nmaster > 1 for NEO/go as that is currently not implemented on NEO/go server

- use json for interacting with runneo.py, so that we can use
  whatever builtin type for any argument without hardcoding ad-hoc
  handling of specific arguments inside runneo.py.

- adjust comments + cosmetics

go/neo/client_test.go

@@ -96,11 +96,11 @@ func (_ *NEOPySrv) BugEncFixed() (bool, proto.Encoding) {
 
 // StartNEOPySrv starts NEO/py server specified by options.
 func StartNEOPySrv(opt NEOSrvOptions) (_ *NEOPySrv, err error) {
-	workdir := opt.workdir
-	defer xerr.Contextf(&err, "start neo/py %s/%s", workdir, opt.name)
+	defer xerr.Contextf(&err, "start neo/py %s", opt)
 
 	ctx, cancel := context.WithCancel(context.Background())
 
+	workdir := opt.workdir
 	readyf := workdir + "/ready"
 	err = os.Remove(readyf)
 	if os.IsNotExist(err) {
@@ -113,12 +113,11 @@ func StartNEOPySrv(opt NEOSrvOptions) (_ *NEOPySrv, err error) {
 	n := &NEOPySrv{opt: opt, cancel: cancel, done: make(chan struct{})}
 
 	// TODO set $PYTHONPATH to top, so that `import neo` works without `pip install -e .`
-	n.pysrv = xexec.Command("./py/runneo.py", workdir, opt.name)
-	n.pysrv.Args = append(n.pysrv.Args, "master_count="+fmt.Sprintf("%v", opt.nmaster))
+	n.pysrv = xexec.Command("./py/runneo.py", workdir, opt.name, "master_count="+fmt.Sprintf("%d", opt.nmaster))
 	if opt.SSL {
-		n.pysrv.Args = append(n.pysrv.Args, "ca="  +opt.CA())
-		n.pysrv.Args = append(n.pysrv.Args, "cert="+opt.Cert())
-		n.pysrv.Args = append(n.pysrv.Args, "key=" +opt.Key())
+		n.pysrv.Args = append(n.pysrv.Args, fmt.Sprintf("ca=%q",   opt.CA()))
+		n.pysrv.Args = append(n.pysrv.Args, fmt.Sprintf("cert=%q", opt.Cert()))
+		n.pysrv.Args = append(n.pysrv.Args, fmt.Sprintf("key=%q",  opt.Key()))
 	}
 	// $TEMP -> workdir  (else NEO/py creates another one for e.g. coverage)
 	n.pysrv.Env = append(os.Environ(), "TEMP="+workdir)
@@ -161,12 +160,12 @@ func StartNEOPySrv(opt NEOSrvOptions) (_ *NEOPySrv, err error) {
 		time.Sleep(10*time.Millisecond)
 	}
 
-	// retrieve master address
-	masterAddr, err := ioutil.ReadFile(readyf)
+	// retrieve masters addresses
+	maddrv, err := ioutil.ReadFile(readyf)
 	if err != nil {
 		return nil, err
 	}
-	n.masterAddrSlice = strings.Split(string(masterAddr), " ")
+	n.masterAddrSlice = strings.Split(string(maddrv), " ")
 
 	return n, nil
 }
@@ -254,7 +253,10 @@ func (_ *NEOGoSrv) BugEncFixed() (bool, proto.Encoding) {
 
 // StartNEOGoSrv starts NEO/go server specified by options.
 func StartNEOGoSrv(opt NEOSrvOptions) (_ *NEOGoSrv, err error) {
-	defer xerr.Contextf(&err, "start neo/go %s/%s", opt.workdir, opt.name)
+	defer xerr.Contextf(&err, "start neo/go %s", opt)
+	if opt.nmaster > 1 {
+		return nil, fmt.Errorf("TODO: nmaster > 1 not implemented")
+	}
 
 	ctx, cancel := context.WithCancel(context.Background())
 	serveWG := xsync.NewWorkGroup(ctx)
@@ -367,6 +369,13 @@ func (n *NEOGoSrv) URL() string {
 
 const npytests = "../../neo/tests/"
 
+// String returns human-readble representation of server options.
+func (opt NEOSrvOptions) String() string {
+	s := fmt.Sprintf("%s/%s M%d ", opt.workdir, opt.name, opt.nmaster)
+	if opt.SSL { s += "ssl" } else { s += "!ssl" }
+	return s
+}
+
 // CA/Cert/Key files to use if opt.SSL=y; empty if SSL=n.
 func (opt NEOSrvOptions) CA() string {
 	if !opt.SSL { return "" }
@@ -442,8 +451,8 @@ func withNEOSrv(t *testing.T, f func(t *testing.T, nsrv NEOSrv), optv ...tOption
 	for _, nmaster := range []int{1, 1} {
 
 		for _, ssl := range []bool{false, true} {
-			kind := ""
-			if ssl { kind = "ssl" } else { kind = "!ssl" }
+			kind := fmt.Sprintf("M%d/", nmaster)
+			if ssl { kind += "ssl" } else { kind += "!ssl" }
 
 			neoOpt := NEOSrvOptions{
 				name:    "1",
@@ -504,6 +513,9 @@ func withNEOSrv(t *testing.T, f func(t *testing.T, nsrv NEOSrv), optv ...tOption
 			// NEO/go
 			t.Run("go/"+kind, func(t *testing.T) {
 				t.Helper()
+				if neoOpt.nmaster > 1 {
+					t.Skip("nmaster > 1 is TODO for NEO/go server")
+				}
 				inWorkDir(t, func(workdir string) {
 					X := xtesting.FatalIf(t)
 

go/neo/py/runneo.py

 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
-# Copyright (C) 2020-2021  Nexedi SA and Contributors.
+# Copyright (C) 2020-2023  Nexedi SA and Contributors.
 #                          Kirill Smelkov <kirr@nexedi.com>
 #
 # This program is free software: you can Use, Study, Modify and Redistribute
@@ -24,14 +24,14 @@ Usage: runneo.py <workdir> <cluster-name>   [k1=v1] [k2=v2] ...
 
 {k->v} dict is optional arguments for NEOCluster.
 
-<workdir>/ready is created with address of master after spawned cluster becomes
+<workdir>/ready is created with addresses of masters after spawned cluster becomes
 operational.
 """
 
 from neo.tests.functional import NEOCluster
 from golang import func, defer
 
-import sys, os
+import sys, os, json
 from time import sleep
 from signal import signal, SIGTERM
 
@@ -45,9 +45,7 @@ def main():
     kw = {'clear_databases': False} # switch default not to clear data on startup
     for arg in sys.argv[3:]:
         k, v = arg.split('=')
-        # We need to cast specific argument to specific types
-        if k in ("master_count",):
-            v = int(v)
+        v = json.loads(v)
         kw[k] = v
 
 
@@ -82,7 +80,7 @@ def main():
 
     # dump information about ready cluster into readyf
     with open("%s.tmp" % readyf, "w") as f:
-        f.write(cluster.master_nodes)    # XXX ' ' separated if multiple masters
+        f.write(cluster.master_nodes)    # NOTE ' ' separated if multiple masters
     os.rename("%s.tmp" % readyf, readyf) # atomic
 
     def _():