Add unit test to function GetCPUVariantFromArch

Add unit test to function GetCPUVariantFromArch
Fix import issue on non-linux platforms
Fix some style issue

Signed-off-by: Tony Fang <nenghui.fang@gmail.com>

platforms/cpuinfo_linux_test.go

@@ -17,8 +17,11 @@
 package platforms
 
 import (
+	"errors"
 	"runtime"
 	"testing"
+
+	"github.com/containerd/containerd/errdefs"
 )
 
 func TestCPUVariant(t *testing.T) {
@@ -30,24 +33,109 @@ func TestCPUVariant(t *testing.T) {
 
 	p, err := getCPUVariant()
 	if err != nil {
-		t.Fatalf("Error getting CPU variant: %v\n", err)
+		t.Fatalf("Error getting CPU variant: %v", err)
 		return
 	}
 
 	for _, variant := range variants {
 		if p == variant {
-			t.Logf("got valid variant as expected: %#v = %#v\n", p, variant)
+			t.Logf("got valid variant as expected: %#v = %#v", p, variant)
 			return
 		}
 	}
 
-	t.Fatalf("could not get valid variant as expected: %v\n", variants)
+	t.Fatalf("could not get valid variant as expected: %v", variants)
 }
 
 func TestGetCPUVariantFromArch(t *testing.T) {
 
-	if !isArmArch(runtime.GOARCH) {
-		t.Skip("only relevant on linux/arm")
-	}
+	for _, testcase := range []struct {
+		name        string
+		input       string
+		output      string
+		expectedErr error
+	}{
+		{
+			name:        "Test aarch64",
+			input:       "aarch64",
+			output:      "8",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test Armv8 with capital",
+			input:       "Armv8",
+			output:      "8",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test armv7",
+			input:       "armv7",
+			output:      "7",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test armv6",
+			input:       "armv6",
+			output:      "6",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test armv5",
+			input:       "armv5",
+			output:      "5",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test armv4",
+			input:       "armv4",
+			output:      "4",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test armv3",
+			input:       "armv3",
+			output:      "3",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test unknown input",
+			input:       "armv9",
+			output:      "unknown",
+			expectedErr: nil,
+		},
+		{
+			name:        "Test invalid input which doesn't start with armv",
+			input:       "armxxxx",
+			output:      "",
+			expectedErr: errdefs.ErrInvalidArgument,
+		},
+		{
+			name:        "Test invalid input whose length is less than 5",
+			input:       "armv",
+			output:      "",
+			expectedErr: errdefs.ErrInvalidArgument,
+		},
+	} {
+		t.Run(testcase.name, func(t *testing.T) {
+			t.Logf("input: %v", testcase.input)
 
+			variant, err := getCPUVariantFromArch(testcase.input)
+
+			if err == nil {
+				if testcase.expectedErr != nil {
+					t.Fatalf("Expect to get error: %v, however no error got", testcase.expectedErr)
+				} else {
+					if variant != testcase.output {
+						t.Fatalf("Expect to get variant: %v, however %v returned", testcase.output, variant)
+					}
+				}
+
+			} else {
+				if !errors.Is(err, testcase.expectedErr) {
+					t.Fatalf("Expect to get error: %v, however error %v returned", testcase.expectedErr, err)
+				}
+			}
+		})
+
+	}
 }