client_test/NEOSrv += LogContent for better debug

If tests fail we may want to check NEO logs. The new function LogContent
of the NEOSrv interface provides an API to fetch the relevant parts of
the log file of a NEO server. This API can be used by test code in order
to automatically print relevant server log information if a test fails.

go/neo/client_test.go

@@ -27,6 +27,7 @@ import (
 	"net/url"
 	"os"
 	"os/exec"
+	"strings"
 	"testing"
 	"time"
 
@@ -54,6 +55,8 @@ type NEOSrv interface {
 	// BugEncFixed reports whether server, instead of autodetection,
 	// supports only fixed encoding, and, if yes, which one.
 	BugEncFixed() (bool, proto.Encoding)
+
+	LogContent() (string, error) // content of log files
 }
 
 // NEOSrvOptions represents options for a NEO server.
@@ -90,6 +93,7 @@ func (_ *NEOPySrv) BugEncFixed() (bool, proto.Encoding) {
 	return true, 'N' // NEO/py 1.12
 }
 
+
 // StartNEOPySrv starts NEO/py server specified by options.
 func StartNEOPySrv(opt NEOSrvOptions) (_ *NEOPySrv, err error) {
 	workdir := opt.workdir
@@ -174,6 +178,37 @@ func (n *NEOPySrv) URL() string {
 	return fmt.Sprintf("%s%s/%s", n.opt.URLPrefix(), n.masterAddr, n.clusterName())
 }
 
+func (n *NEOPySrv) LogContent() (string, error) {
+	scontent, err := n.logFileContent("storage_0.log")
+	if err != nil {
+		return "", err
+	}
+	mcontent, err := n.logFileContent("master_0.log")
+	if err != nil {
+		return "", err
+	}
+	return scontent + "\n\n" + mcontent, nil
+}
+
+func (n *NEOPySrv) logFileContent(logfilename string) (string, error) {
+	c := xexec.Command("./py/neolog", fmt.Sprintf("%s/%s", n.opt.workdir, logfilename))
+	o, err := c.Output()
+	if err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("log file '%s' content:\n\n", logfilename) + tail(string(o)), nil
+}
+
+func tail(s string) (string) {
+	sslice := strings.Split(s, "\n")
+	icount := len(sslice)
+	tailsize := 20
+	if icount < tailsize {
+		tailsize = icount
+	}
+	return strings.Join(sslice[icount - tailsize:], "\n")
+}
+
 func (n *NEOPySrv) Close() (err error) {
 	defer xerr.Contextf(&err, "stop neo/py %s", n.opt.workdir)
 
@@ -281,6 +316,10 @@ func StartNEOGoSrv(opt NEOSrvOptions) (_ *NEOGoSrv, err error) {
 	return n, nil
 }
 
+func (n *NEOGoSrv) LogContent() (string, error) {
+	return "", nil
+}
+
 func (n *NEOGoSrv) Close() (err error) {
 	defer xerr.Contextf(&err, "stop neo/go %s", n.opt.workdir)
 

go/neo/py/neolog

+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+import re
+import sys
+from neo.scripts.neolog import main
+if __name__ == '__main__':
+    sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
+    sys.exit(main())