combine suggested commit and add unit test

Signed-off-by: Songpon Srisawai <[email protected]>

Author: songponssw

pkg/limayaml/validate.go

@@ -612,13 +612,14 @@ func warnExperimental(y *LimaYAML) {
 }
 
 // ValidateYAMLAgainstLatestConfig validates the values between the latest YAML and the updated(New) YAML.
+// This validates configuration rules that disallow certain changes, such as shrinking the disk.
 func ValidateYAMLAgainstLatestConfig(yNew, yLatest []byte) error {
 	var l, n LimaYAML
-	var err error
-	if err = Unmarshal(yLatest, &l, "Unmarshal latest YAML bytes"); err != nil {
+
+	if err := Unmarshal(yLatest, &l, "Unmarshal latest YAML bytes"); err != nil {
 		return err
 	}
-	if err = Unmarshal(yNew, &n, "Unmarshal new YAML bytes); err != nil {
+	if err := Unmarshal(yNew, &n, "Unmarshal new YAML bytes"); err != nil {
 		return err
 	}
 

pkg/limayaml/validate_test.go

@@ -264,3 +264,28 @@ provision:
 		"field `provision[0].mode` must one of \"system\", \"user\", \"boot\", \"data\", \"dependency\", or \"ansible\"\n"+
 		"field `provision[1].path` must not be empty when mode is \"data\"")
 }
+
+// TestValidateAgainstLatestConfig ensures the new config is correctly validated against the latest config.
+// (e.g., disk shrinking is disallowed).
+func TestValidateAgainstLatestConfig(t *testing.T) {
+	validParam := [][]string{
+		{`disk: 100G`, `disk: 100G`},
+		{`disk: 200G`, `disk: 100G`},
+		{``, ``},
+	}
+	for _, param := range validParam {
+		n, l := param[0], param[1]
+		err := ValidateYAMLAgainstLatestConfig([]byte(n), []byte(l))
+		assert.NilError(t, err)
+	}
+
+	invalidParam := [][]string{
+		{`disk: 50G`, `disk: 100G`, `shrinking`},
+	}
+
+	for _, param := range invalidParam {
+		n, l := param[0], param[1]
+		err := ValidateYAMLAgainstLatestConfig([]byte(n), []byte(l))
+		assert.ErrorContains(t, err, param[2])
+	}
+}