Improve the default values for int based environment vars

lambda/main.go

@@ -95,20 +95,12 @@ func Handler(ctx context.Context, evt json.RawMessage) (string, error) {
 		queues = strings.Split(queue, ",")
 	}
 
-	if timeout == "" {
-		timeout = "15"
-	}
-
-	if maxIdleConns == "" {
-		maxIdleConns = "100" // Default to 100 in line with http.DefaultTransport
-	}
-
-	configuredTimeout, err := strconv.Atoi(timeout)
+	configuredTimeout, err := toIntWithDefault(timeout, 15)
 	if err != nil {
 		return "", err
 	}
 
-	configuredMaxIdleConns, err := strconv.Atoi(maxIdleConns)
+	configuredMaxIdleConns, err := toIntWithDefault(maxIdleConns, 100)
 	if err != nil {
 		return "", err
 	}
@@ -283,3 +275,11 @@ func checkMutuallyExclusiveEnvVars(varNames ...string) error {
 		return fmt.Errorf("the environment variables [%s] are mutually exclusive", strings.Join(foundVars, ","))
 	}
 }
+
+func toIntWithDefault(val string, defaultVal int) (int, error) {
+	if val == "" {
+		return defaultVal, nil
+	}
+
+	return strconv.Atoi(val)
+}

lambda/main_test.go

@@ -0,0 +1,43 @@
+package main
+
+import "testing"
+
+func Test_toIntWithDefault(t *testing.T) {
+	type args struct {
+		value    string
+		defaults int
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    int
+		wantErr bool
+	}{
+		{
+			name: "empty",
+			args: args{value: "", defaults: 10},
+			want: 10,
+		},
+		{
+			name:    "invalid",
+			args:    args{value: "invalid", defaults: 10},
+			wantErr: true,
+		},
+		{
+			name: "valid",
+			args: args{value: "20", defaults: 10},
+			want: 20,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got, err := toIntWithDefault(tt.args.value, tt.args.defaults); (err != nil) != tt.wantErr {
+				t.Errorf("toIntWithDefault() error = %v, wantErr %v", err, tt.wantErr)
+			} else {
+				if got != tt.want {
+					t.Errorf("toIntWithDefault() = %v, want %v", got, tt.want)
+				}
+			}
+		})
+	}
+}