test: add UT for gen-disk-skus-map_test

pkg/tool/gen-disk-skus-map.go

@@ -49,6 +49,11 @@ func init() {
 	klog.InitFlags(nil)
 }
 
+// exit is a separate function to handle program termination
+var exit = func(code int) {
+	os.Exit(code)
+}
+
 func main() {
 
 	boilerPlate := `/*
@@ -137,7 +142,7 @@ import (
 			diskSkuInfoMap[account][diskSize], err = getDiskCapabilities(sku)
 			if err != nil {
 				klog.Errorf("populateSkuMap: Failed to get disk capabilities for disk %s %s %s. Error: %v", *sku.Name, *sku.Size, *sku.Tier, err)
-				os.Exit(1)
+				exit(1)
 			}
 		} else if resType == "virtualmachines" {
 
@@ -146,7 +151,7 @@ import (
 			err = populateNodeCapabilities(sku, &nodeInfo)
 			if err != nil {
 				klog.Errorf("populateSkuMap: Failed to populate node capabilities. Error: %v", err)
-				os.Exit(1)
+				exit(1)
 			}
 			vmSkuInfoMap[strings.ToLower(*sku.Name)] = nodeInfo
 		}

pkg/tool/gen-disk-skus-map_test.go

@@ -0,0 +1,49 @@
+/*
+Copyright 2024 The Kubernetes 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 main
+
+import (
+	"os"
+	"testing"
+)
+
+func TestMain(t *testing.T) {
+	// Capture stdout
+	old := os.Stdout
+	_, w, _ := os.Pipe()
+	os.Stdout = w
+
+	// Replace exit function with mock function
+	var exitCode int
+	exit = func(code int) {
+		exitCode = code
+	}
+
+	// Call main function
+	main()
+
+	// Restore stdout
+	w.Close()
+	os.Stdout = old
+	exit = func(code int) {
+		os.Exit(code)
+	}
+
+	if exitCode != 0 {
+		t.Errorf("Expected exit code 0, but got %d", exitCode)
+	}
+}