pkg/testutil: add RandSource helper

The code to send rand source is dublicated in several packages.
Move it to testutil package.

5 files changed, 31 insertions, 30 deletions

diff --git a/pkg/csource/csource_test.go b/pkg/csource/csource_test.go
index bfeb8f6a7..2d047cc10 100644
--- a/pkg/csource/csource_test.go
+++ b/pkg/csource/csource_test.go
@@ -12,7 +12,6 @@ import (
 	"strings"
 	"sync/atomic"
 	"testing"
-	"time"
 
 	"github.com/google/syzkaller/pkg/testutil"
 	"github.com/google/syzkaller/prog"
@@ -59,12 +58,7 @@ func TestGenerate(t *testing.T) {
 }
 
 func testTarget(t *testing.T, target *prog.Target, full bool) {
-	seed := time.Now().UnixNano()
-	if os.Getenv("CI") != "" {
-		seed = 0 // required for deterministic coverage reports
-	}
-	rs := rand.NewSource(seed)
-	t.Logf("seed=%v", seed)
+	rs := testutil.RandSource(t)
 	p := target.Generate(rs, 10, target.DefaultChoiceTable())
 	// Turns out that fully minimized program can trigger new interesting warnings,
 	// e.g. about NULL arguments for functions that require non-NULL arguments in syz_ functions.
diff --git a/pkg/ifuzz/ifuzz_test.go b/pkg/ifuzz/ifuzz_test.go
index eee8afe00..11f57216b 100644
--- a/pkg/ifuzz/ifuzz_test.go
+++ b/pkg/ifuzz/ifuzz_test.go
@@ -6,11 +6,10 @@ package ifuzz
 import (
 	"encoding/hex"
 	"math/rand"
-	"os"
 	"testing"
-	"time"
 
 	"github.com/google/syzkaller/pkg/ifuzz/iset"
+	"github.com/google/syzkaller/pkg/testutil"
 )
 
 var allArches = []string{ArchX86, ArchPowerPC}
@@ -53,12 +52,7 @@ func testDecode(t *testing.T, arch string) {
 	if _, err := insnset.DecodeExt(0, nil); err == nil {
 		xedEnabled = true
 	}
-	seed := time.Now().UnixNano()
-	if os.Getenv("CI") != "" {
-		seed = 0 // required for deterministic coverage reports
-	}
-	t.Logf("seed=%v", seed)
-	r := rand.New(rand.NewSource(seed))
+	r := rand.New(testutil.RandSource(t))
 
 	for repeat := 0; repeat < 10; repeat++ {
 		for mode := iset.Mode(0); mode < iset.ModeLast; mode++ {
diff --git a/pkg/ipc/ipc_test.go b/pkg/ipc/ipc_test.go
index 3456852c5..0734fbe6e 100644
--- a/pkg/ipc/ipc_test.go
+++ b/pkg/ipc/ipc_test.go
@@ -16,6 +16,7 @@ import (
 	. "github.com/google/syzkaller/pkg/ipc"
 	"github.com/google/syzkaller/pkg/ipc/ipcconfig"
 	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/google/syzkaller/pkg/testutil"
 	"github.com/google/syzkaller/prog"
 	_ "github.com/google/syzkaller/sys"
 	"github.com/google/syzkaller/sys/targets"
@@ -36,12 +37,6 @@ func initTest(t *testing.T) (*prog.Target, rand.Source, int, bool, bool, targets
 	if testing.Short() {
 		iters = 10
 	}
-	seed := time.Now().UnixNano()
-	if os.Getenv("CI") != "" {
-		seed = 0 // required for deterministic coverage reports
-	}
-	rs := rand.NewSource(seed)
-	t.Logf("seed=%v", seed)
 	target, err := prog.GetTarget(runtime.GOOS, runtime.GOARCH)
 	if err != nil {
 		t.Fatal(err)
@@ -50,6 +45,7 @@ func initTest(t *testing.T) (*prog.Target, rand.Source, int, bool, bool, targets
 	if err != nil {
 		t.Fatal(err)
 	}
+	rs := testutil.RandSource(t)
 	return target, rs, iters, cfg.UseShmem, cfg.UseForkServer, cfg.Timeouts
 }
 
diff --git a/pkg/repro/repro_test.go b/pkg/repro/repro_test.go
index d02ea6d67..486dc963b 100644
--- a/pkg/repro/repro_test.go
+++ b/pkg/repro/repro_test.go
@@ -5,11 +5,10 @@ package repro
 
 import (
 	"math/rand"
-	"os"
 	"testing"
-	"time"
 
 	"github.com/google/syzkaller/pkg/csource"
+	"github.com/google/syzkaller/pkg/testutil"
 	"github.com/google/syzkaller/prog"
 	"github.com/google/syzkaller/sys/targets"
 )
@@ -19,13 +18,7 @@ func initTest(t *testing.T) (*rand.Rand, int) {
 	if testing.Short() {
 		iters = 100
 	}
-	seed := time.Now().UnixNano()
-	if os.Getenv("CI") != "" {
-		seed = 0 // required for deterministic coverage reports
-	}
-	rs := rand.NewSource(seed)
-	t.Logf("seed=%v", seed)
-	return rand.New(rs), iters
+	return rand.New(testutil.RandSource(t)), iters
 }
 
 func TestBisect(t *testing.T) {
diff --git a/pkg/testutil/testutil.go b/pkg/testutil/testutil.go
new file mode 100644
index 000000000..9a8de26bd
--- /dev/null
+++ b/pkg/testutil/testutil.go
@@ -0,0 +1,24 @@
+// Copyright 2022 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+package testutil
+
+import (
+	"math/rand"
+	"os"
+	"strconv"
+	"testing"
+	"time"
+)
+
+func RandSource(t *testing.T) rand.Source {
+	seed := time.Now().UnixNano()
+	if fixed := os.Getenv("SYZ_SEED"); fixed != "" {
+		seed, _ = strconv.ParseInt(fixed, 0, 64)
+	}
+	if os.Getenv("CI") != "" {
+		seed = 0 // required for deterministic coverage reports
+	}
+	t.Logf("seed=%v", seed)
+	return rand.NewSource(seed)
+}