pkg/manager: add a test for PatchFocusAreas

For that, make a part of the tar_test.go reusable.

1 files changed, 68 insertions, 0 deletions

diff --git a/pkg/manager/diff_test.go b/pkg/manager/diff_test.go
new file mode 100644
index 000000000..f2408f13b
--- /dev/null
+++ b/pkg/manager/diff_test.go
@@ -0,0 +1,68 @@
+// Copyright 2025 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 manager
+
+import (
+	"testing"
+
+	"github.com/google/syzkaller/pkg/mgrconfig"
+	"github.com/google/syzkaller/pkg/osutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPatchFocusAreas(t *testing.T) {
+	cfg := &mgrconfig.Config{
+		KernelSrc: t.TempDir(),
+	}
+	require.NoError(t, osutil.FillDirectory(cfg.KernelSrc, map[string]string{
+		"header.h": `Test`,
+		"a.c": `#include <header.h>
+int main(void) { }`,
+		"b.c": `int main(void) { }`,
+		"c.c": `int main(void) { }`,
+	}))
+
+	PatchFocusAreas(cfg, [][]byte{
+		[]byte(`diff --git a/b.c b/b.c
+index 103167d..fbf7a68 100644
+--- a/b.c
++++ b/b.c
+@@ -1 +1 @@
+-int main(void) { }
+\ No newline at end of file
++int main(void) { return 1; }
+\ No newline at end of file`),
+		// Also, emulate an update to te header.h.
+		[]byte(`diff --git a/header.h b/header.h
+index 103167d..fbf7a68 100644
+--- a/header.h
++++ b/header.h
+@@ -1 +1 @@
+-Test
+\ No newline at end of file
++Test2
+\ No newline at end of file`),
+	})
+
+	assert.Equal(t, []mgrconfig.FocusArea{
+		{
+			Name: modifiedArea,
+			Filter: mgrconfig.CovFilterCfg{
+				Files: []string{"b.c", "header.h"},
+			},
+			Weight: 3.0,
+		},
+		{
+			Name: includesArea,
+			Filter: mgrconfig.CovFilterCfg{
+				Files: []string{"a.c"},
+			},
+			Weight: 2.0,
+		},
+		{
+			Weight: 1.0,
+		},
+	}, cfg.Experimental.FocusAreas)
+}