test: add unit test for func MaxQemuVCPUs

we should add unit test for func MaxQemuVCPUS in qemu_amd64_test.go

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Signed-off-by: Wei Chen <Wei.Chen@arm.com>

virtcontainers/qemu_arm64_test.go

@@ -7,6 +7,10 @@ package virtcontainers
 
 import (
 	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"runtime"
 	"testing"
 
 	govmmQemu "github.com/intel/govmm/qemu"
@@ -50,3 +54,52 @@ func TestQemuArm64MemoryTopology(t *testing.T) {
 	m := arm64.memoryTopology(mem, hostMem)
 	assert.Equal(expectedMemory, m)
 }
+
+func TestMaxQemuVCPUs(t *testing.T) {
+	assert := assert.New(t)
+
+	type testData struct {
+		contents       string
+		expectedResult uint32
+	}
+
+	data := []testData{
+		{"", uint32(runtime.NumCPU())},
+		{"  1:          0          0     GICv2  25 Level     vgic \n", uint32(8)},
+		{"  1:          0          0     GICv3  25 Level     vgic \n", uint32(123)},
+		{"  1:          0          0     GICv4  25 Level     vgic \n", uint32(123)},
+	}
+
+	tmpdir, err := ioutil.TempDir("", "")
+	if err != nil {
+		panic(err)
+	}
+	defer os.RemoveAll(tmpdir)
+
+	savedGicProfile := gicProfile
+
+	testGicProfile := filepath.Join(tmpdir, "interrupts")
+
+	// override
+	gicProfile = testGicProfile
+
+	defer func() {
+		gicProfile = savedGicProfile
+	}()
+
+	savedHostGICVersion := hostGICVersion
+
+	defer func() {
+		hostGICVersion = savedHostGICVersion
+	}()
+
+	for _, d := range data {
+		err := ioutil.WriteFile(gicProfile, []byte(d.contents), os.FileMode(0640))
+		assert.NoError(err)
+
+		hostGICVersion = getHostGICVersion()
+		vCPUs := MaxQemuVCPUs()
+
+		assert.Equal(d.expectedResult, vCPUs)
+	}
+}