Use enum instead of string as issue severity

helper/runner_test.go

@@ -280,7 +280,7 @@ type dummyRule struct {
 
 func (r *dummyRule) Name() string              { return "dummy_rule" }
 func (r *dummyRule) Enabled() bool             { return true }
-func (r *dummyRule) Severity() string          { return tflint.ERROR }
+func (r *dummyRule) Severity() tflint.Severity { return tflint.ERROR }
 func (r *dummyRule) Check(tflint.Runner) error { return nil }
 
 func Test_EmitIssueOnExpr(t *testing.T) {

plugin/fromproto/fromproto.go

@@ -89,7 +89,7 @@ type RuleObject struct {
 	Data struct {
 		Name     string
 		Enabled  bool
-		Severity string
+		Severity tflint.Severity
 		Link     string
 	}
 }
@@ -101,7 +101,7 @@ func (r *RuleObject) Name() string { return r.Data.Name }
 func (r *RuleObject) Enabled() bool { return r.Data.Enabled }
 
 // Severity returns the severify of the rule
-func (r *RuleObject) Severity() string { return r.Data.Severity }
+func (r *RuleObject) Severity() tflint.Severity { return r.Data.Severity }
 
 // Link returns the link of the rule documentation if exists
 func (r *RuleObject) Link() string { return r.Data.Link }
@@ -119,7 +119,7 @@ func Rule(rule *proto.EmitIssue_Rule) *RuleObject {
 		Data: struct {
 			Name     string
 			Enabled  bool
-			Severity string
+			Severity tflint.Severity
 			Link     string
 		}{
 			Name:     rule.Name,
@@ -131,7 +131,7 @@ func Rule(rule *proto.EmitIssue_Rule) *RuleObject {
 }
 
 // Severity converts proto.EmitIssue_Severity to severity
-func Severity(severity proto.EmitIssue_Severity) string {
+func Severity(severity proto.EmitIssue_Severity) tflint.Severity {
 	switch severity {
 	case proto.EmitIssue_SEVERITY_ERROR:
 		return tflint.ERROR

plugin/toproto/toproto.go

@@ -97,7 +97,7 @@ func Rule(rule tflint.Rule) *proto.EmitIssue_Rule {
 }
 
 // Severity converts severity to proto.EmitIssue_Severity
-func Severity(severity string) proto.EmitIssue_Severity {
+func Severity(severity tflint.Severity) proto.EmitIssue_Severity {
 	switch severity {
 	case tflint.ERROR:
 		return proto.EmitIssue_SEVERITY_ERROR

tflint/interface.go

@@ -63,7 +63,7 @@ type Rule interface {
 	Enabled() bool
 
 	// Severity indicates the severity of the rule.
-	Severity() string
+	Severity() Severity
 
 	// Link allows you to add a reference link to the rule.
 	Link() string

tflint/issue.go

@@ -1,11 +1,27 @@
 package tflint
 
-// List of issue severity levels. The rules implemented by a plugin can be set to any severity.
+// Severity indicates the severity of the issue.
+type Severity int32
+
 const (
 	// ERROR is possible errors
-	ERROR = "Error"
+	ERROR Severity = iota
 	// WARNING doesn't cause problem immediately, but not good
-	WARNING = "Warning"
+	WARNING
 	// NOTICE is not important, it's mentioned
-	NOTICE = "Notice"
+	NOTICE
 )
+
+// String returns the string representation of the severity.
+func (s Severity) String() string {
+	switch s {
+	case ERROR:
+		return "Error"
+	case WARNING:
+		return "Warning"
+	case NOTICE:
+		return "Notice"
+	}
+
+	return "Unknown"
+}

tflint/rule.go

@@ -26,5 +26,5 @@ type embedDefaultRule struct {
 
 func (r *embedDefaultRule) Name() string              { return "" }
 func (r *embedDefaultRule) Enabled() bool             { return true }
-func (r *embedDefaultRule) Severity() string          { return ERROR }
+func (r *embedDefaultRule) Severity() Severity        { return ERROR }
 func (r *embedDefaultRule) Check(runner Runner) error { return nil }