Merge pull request #40269 from tanshanshan/unittest-scheduler-default

Automatic merge from submit-queue (batch tested with PRs 41937, 41151, 42092, 40269, 42135)

Improve code coverage for scheduler/algorithmprovider/defaults

**What this PR does / why we need it**:

Improve code coverage for scheduler/algorithmprovider/defaults from #39559

Thanks for your review.
**Special notes for your reviewer**:

**Release note**:

```release-note
```

plugin/pkg/scheduler/algorithmprovider/defaults/BUILD

@@ -28,7 +28,10 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["compatibility_test.go"],
+    srcs = [
+        "compatibility_test.go",
+        "defaults_test.go",
+    ],
     library = ":go_default_library",
     tags = ["automanaged"],
     deps = [

plugin/pkg/scheduler/algorithmprovider/defaults/defaults.go

@@ -41,6 +41,7 @@ const (
 	DefaultMaxAzureDiskVolumes = 16
 	ClusterAutoscalerProvider  = "ClusterAutoscalerProvider"
 	StatefulSetKind            = "StatefulSet"
+	KubeMaxPDVols              = "KUBE_MAX_PD_VOLS"
 )
 
 func init() {
@@ -217,7 +218,7 @@ func defaultPriorities() sets.String {
 
 // getMaxVols checks the max PD volumes environment variable, otherwise returning a default value
 func getMaxVols(defaultVal int) int {
-	if rawMaxVols := os.Getenv("KUBE_MAX_PD_VOLS"); rawMaxVols != "" {
+	if rawMaxVols := os.Getenv(KubeMaxPDVols); rawMaxVols != "" {
 		if parsedMaxVols, err := strconv.Atoi(rawMaxVols); err != nil {
 			glog.Errorf("Unable to parse maxiumum PD volumes value, using default of %v: %v", defaultVal, err)
 		} else if parsedMaxVols <= 0 {

plugin/pkg/scheduler/algorithmprovider/defaults/defaults_test.go

@@ -0,0 +1,62 @@
+/*
+Copyright 2017 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 defaults
+
+import (
+	"os"
+	"testing"
+)
+
+func TestGetMaxVols(t *testing.T) {
+	previousValue := os.Getenv(KubeMaxPDVols)
+	defaultValue := 39
+
+	tests := []struct {
+		rawMaxVols string
+		expected   int
+		test       string
+	}{
+		{
+			rawMaxVols: "invalid",
+			expected:   defaultValue,
+			test:       "Unable to parse maxiumum PD volumes value, using default value",
+		},
+		{
+			rawMaxVols: "-2",
+			expected:   defaultValue,
+			test:       "Maximum PD volumes must be a positive value, using default value",
+		},
+		{
+			rawMaxVols: "40",
+			expected:   40,
+			test:       "Parse maximum PD volumes value from env",
+		},
+	}
+
+	for _, test := range tests {
+		os.Setenv(KubeMaxPDVols, test.rawMaxVols)
+		result := getMaxVols(defaultValue)
+		if result != test.expected {
+			t.Errorf("%s: expected %v got %v", test.test, test.expected, result)
+		}
+	}
+
+	os.Unsetenv(KubeMaxPDVols)
+	if previousValue != "" {
+		os.Setenv(KubeMaxPDVols, previousValue)
+	}
+}