diff --git a/env.go b/env.go
index e66c7ca..e1e1e7f 100644
--- a/env.go
+++ b/env.go
@@ -299,7 +299,10 @@ func (e *EnvT) fixtureCallWrapper(key cacheKey, f FixtureCallbackFunc, opt *Fixt
 		e.m.Unlock()
 
 		if si == nil {
-			e.t.Fatalf("Unexpected scope. Create env for test %q", scopeName)
+			if opt.Scope == ScopePackage {
+				e.t.Fatalf("Initialize package scope before use ", scopeName)
+			}
+			e.t.Fatalf("Unexpected scope: %q", scopeName)
 			// not reachable
 			return nil, nil
 		}
diff --git a/examples/simple_main_test/example_test.go b/examples/simple_main_test/example_test.go
new file mode 100644
index 0000000..2cb2f0f
--- /dev/null
+++ b/examples/simple_main_test/example_test.go
@@ -0,0 +1,38 @@
+package simple_main_test
+
+import (
+	"github.com/rekby/fixenv"
+	"math/rand"
+	"testing"
+)
+
+var global int = -1
+
+func FSingleRandom(e fixenv.Env) int {
+	var f fixenv.GenericFixtureFunction[int] = func() (*fixenv.GenericResult[int], error) {
+		return fixenv.NewGenericResult(rand.Int()), nil
+	}
+	return fixenv.CacheResult(e, f, fixenv.CacheOptions{Scope: fixenv.ScopePackage})
+}
+
+func TestFirst(t *testing.T) {
+	e := fixenv.New(t)
+	if global == -1 {
+		global = FSingleRandom(e)
+	}
+
+	if singleRnd := FSingleRandom(e); singleRnd != global {
+		t.Fatalf("%v != %v", singleRnd, global)
+	}
+}
+
+func TestSecond(t *testing.T) {
+	e := fixenv.New(t)
+	if global == -1 {
+		global = FSingleRandom(e)
+	}
+
+	if singleRnd := FSingleRandom(e); singleRnd != global {
+		t.Fatalf("%v != %v", singleRnd, global)
+	}
+}
diff --git a/examples/simple_main_test/testmain_test.go b/examples/simple_main_test/testmain_test.go
new file mode 100644
index 0000000..42580a0
--- /dev/null
+++ b/examples/simple_main_test/testmain_test.go
@@ -0,0 +1,11 @@
+package simple_main
+
+import (
+	"github.com/rekby/fixenv"
+	"os"
+	"testing"
+)
+
+func TestMain(m *testing.M) {
+	os.Exit(fixenv.RunTests(m))
+}
diff --git a/maintest.go b/maintest.go
index 9c54d51..61f0cf2 100644
--- a/maintest.go
+++ b/maintest.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log"
 	"sync"
+	"testing"
 )
 
 // FatalfFunction function signature of Fatalf
@@ -46,6 +47,30 @@ func CreateMainTestEnv(opts *CreateMainTestEnvOpts) (env *EnvT, tearDown func())
 	return env, packageLevelVirtualTest.cleanup
 }
 
+// RunTests runs the tests. It returns an exit code to pass to os.Exit.
+//
+// Usage:
+// declare in _test file TestMain function:
+//
+// func TestMain(m *testing.M) {
+//	 os.Exit(fixenv.RunTests(m))
+// }
+func RunTests(m *testing.M, opts ...*CreateMainTestEnvOpts) int {
+	var options *CreateMainTestEnvOpts
+	switch len(opts) {
+	case 0:
+		// pass
+	case 1:
+		options = opts[0]
+	default:
+		panic("allow not more then one optional arg")
+	}
+
+	_, cancel := CreateMainTestEnv(options)
+	defer cancel()
+	return m.Run()
+}
+
 // virtualTest implement T interface for global env scope
 type virtualTest struct {
 	m       sync.Mutex