diff --git a/pkg/device/metax/score_test.go b/pkg/device/metax/score_test.go
new file mode 100644
index 0000000000..ab3bfd7487
--- /dev/null
+++ b/pkg/device/metax/score_test.go
@@ -0,0 +1,173 @@
+/*
+Copyright 2025 The HAMi Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+	http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package metax
+
+import "testing"
+
+func TestLinkDeviceScore(t *testing.T) {
+	for _, ts := range []struct {
+		name     string
+		from     *LinkDevice
+		to       *LinkDevice
+		expected int
+	}{
+		{
+			name:     "same uuid returns zero",
+			from:     &LinkDevice{uuid: "GPU-0", linkZone: 1},
+			to:       &LinkDevice{uuid: "GPU-0", linkZone: 1},
+			expected: 0,
+		},
+		{
+			name:     "from linkZone zero returns zero",
+			from:     &LinkDevice{uuid: "GPU-0", linkZone: 0},
+			to:       &LinkDevice{uuid: "GPU-1", linkZone: 1},
+			expected: 0,
+		},
+		{
+			name:     "to linkZone zero returns zero",
+			from:     &LinkDevice{uuid: "GPU-0", linkZone: 1},
+			to:       &LinkDevice{uuid: "GPU-1", linkZone: 0},
+			expected: 0,
+		},
+		{
+			name:     "both linkZone zero returns zero",
+			from:     &LinkDevice{uuid: "GPU-0", linkZone: 0},
+			to:       &LinkDevice{uuid: "GPU-1", linkZone: 0},
+			expected: 0,
+		},
+		{
+			name:     "same linkZone returns direct link score",
+			from:     &LinkDevice{uuid: "GPU-0", linkZone: 1},
+			to:       &LinkDevice{uuid: "GPU-1", linkZone: 1},
+			expected: DirectLinkScore,
+		},
+		{
+			name:     "different linkZone returns zero",
+			from:     &LinkDevice{uuid: "GPU-0", linkZone: 1},
+			to:       &LinkDevice{uuid: "GPU-1", linkZone: 2},
+			expected: 0,
+		},
+	} {
+		t.Run(ts.name, func(t *testing.T) {
+			result := ts.from.score(ts.to)
+			if result != ts.expected {
+				t.Fatalf("score() failed: result %v, expected %v", result, ts.expected)
+			}
+		})
+	}
+}
+
+func TestLinkDevicesScore(t *testing.T) {
+	for _, ts := range []struct {
+		name     string
+		devs     LinkDevices
+		expected int
+	}{
+		{
+			name:     "empty devices",
+			devs:     LinkDevices{},
+			expected: 0,
+		},
+		{
+			name: "single device",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 1},
+			},
+			expected: 0,
+		},
+		{
+			name: "two devices same zone",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 1},
+				{uuid: "GPU-1", linkZone: 1},
+			},
+			expected: DirectLinkScore,
+		},
+		{
+			name: "two devices different zone",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 1},
+				{uuid: "GPU-1", linkZone: 2},
+			},
+			expected: 0,
+		},
+		{
+			name: "three devices all same zone sums pairwise",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 1},
+				{uuid: "GPU-1", linkZone: 1},
+				{uuid: "GPU-2", linkZone: 1},
+			},
+
+			expected: 3 * DirectLinkScore,
+		},
+		{
+			name: "mixed zones only matching pairs score",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 1},
+				{uuid: "GPU-1", linkZone: 1},
+				{uuid: "GPU-2", linkZone: 2},
+			},
+
+			expected: DirectLinkScore,
+		},
+		{
+			name: "devices with zero linkZone never score",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 0},
+				{uuid: "GPU-1", linkZone: 0},
+			},
+			expected: 0,
+		},
+	} {
+		t.Run(ts.name, func(t *testing.T) {
+			result := ts.devs.Score()
+			if result != ts.expected {
+				t.Errorf("Score() failed: result %v, expected %v", result, ts.expected)
+			}
+		})
+	}
+}
+
+func TestLinkDevicesString(t *testing.T) {
+	for _, ts := range []struct {
+		name     string
+		devs     LinkDevices
+		expected string
+	}{
+		{
+			name:     "empty devices",
+			devs:     LinkDevices{},
+			expected: "[]",
+		},
+		{
+			name: "non-empty devices produce expected output",
+			devs: LinkDevices{
+				{uuid: "GPU-0", linkZone: 1},
+				{uuid: "GPU-1", linkZone: 2},
+			},
+			expected: "[{GPU-0 1}{GPU-1 2}]",
+		},
+	} {
+		t.Run(ts.name, func(t *testing.T) {
+			result := ts.devs.String()
+			if result != ts.expected {
+				t.Errorf("String() = %q, expected %q", result, ts.expected)
+			}
+		})
+	}
+}