4 files changed, 143 insertions, 38 deletions
diff --git a/internal/feed/feed.go b/internal/feed/feed.go
index 56fc7d2..affa5d2 100644
--- a/internal/feed/feed.go
+++ b/internal/feed/feed.go
@@ -6,47 +6,12 @@ import (
 )
 
 const (
-  None = iota     // no priv req/user interaction
-  Low             // low complexity/priv req
-  Medium          // medium complexity/priv req
-  High            // high complexity/priv req
-
-  Critical        // critical severity
-
-  CvssVersion31   // CVSS version 3.1
-  CvssVersion20   // CVSS version 2.0
-
-  Single          // Single authentication
+  CvssVersion31 = iota  // CVSS version 3.1
+  CvssVersion20 // CVSS version 2.0
 )
 
 // TODO: parse cpe, cve id
 
-// CVSS V2 authentication
-type Authentication int
-
-// Unmarshal CVSS V2 authentication from JSON.
-func (me *Authentication) UnmarshalJSON(b []byte) error {
-  // decode string, check for error
-  var s string
-  if err := json.Unmarshal(b, &s); err != nil {
-    return err
-  }
-
-  // check value
-  switch s {
-  case "NONE":
-    *me = None
-  case "SINGLE":
-    *me = Single
-  default:
-    // return error
-    return fmt.Errorf("unknown authentication: %s", s)
-  }
-
-  // return success
-  return nil
-}
-
 // CVE metadata
 type CveMetadata struct {
   // CVE ID
@@ -267,7 +232,7 @@ type CvssV2 struct {
   AccessComplexity V2AccessComplexity `json:"accessComplexity"`
 
   // authentication
-  Authentication Authentication `json:"authentication"`
+  Authentication V2Authentication `json:"authentication"`
 
   ConfidentialityImpact V2Impact `json:"confidentialityImpact"`
   IntegrityImpact V2Impact `json:"integrityImpact"`
diff --git a/internal/feed/v2authentication.go b/internal/feed/v2authentication.go
new file mode 100644
index 0000000..853954f
--- /dev/null
+++ b/internal/feed/v2authentication.go
@@ -0,0 +1,39 @@
+package feed
+
+//go:generate stringer -linecomment -type=V2Authentication
+
+import (
+  "encoding/json"
+  "fmt"
+)
+
+// CVSS v2 authentication
+type V2Authentication byte
+
+const (
+  V2AuthNone V2Authentication = iota // NONE
+  V2AuthSingle // SINGLE
+)
+
+// Unmarshal CVSS V2 authentication from JSON.
+func (me *V2Authentication) UnmarshalJSON(b []byte) error {
+  // decode string, check for error
+  var s string
+  if err := json.Unmarshal(b, &s); err != nil {
+    return err
+  }
+
+  // check value
+  switch s {
+  case "NONE":
+    *me = V2AuthNone
+  case "SINGLE":
+    *me = V2AuthSingle
+  default:
+    // return error
+    return fmt.Errorf("unknown CVSS v2 authentication: %s", s)
+  }
+
+  // return success
+  return nil
+}
diff --git a/internal/feed/v2authentication_string.go b/internal/feed/v2authentication_string.go
new file mode 100644
index 0000000..856c808
--- /dev/null
+++ b/internal/feed/v2authentication_string.go
@@ -0,0 +1,24 @@
+// Code generated by "stringer -linecomment -type=V2Authentication"; DO NOT EDIT.
+
+package feed
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[V2AuthNone-0]
+	_ = x[V2AuthSingle-1]
+}
+
+const _V2Authentication_name = "NONESINGLE"
+
+var _V2Authentication_index = [...]uint8{0, 4, 10}
+
+func (i V2Authentication) String() string {
+	if i >= V2Authentication(len(_V2Authentication_index)-1) {
+		return "V2Authentication(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _V2Authentication_name[_V2Authentication_index[i]:_V2Authentication_index[i+1]]
+}
diff --git a/internal/feed/v2authentication_test.go b/internal/feed/v2authentication_test.go
new file mode 100644
index 0000000..4f23764
--- /dev/null
+++ b/internal/feed/v2authentication_test.go
@@ -0,0 +1,77 @@
+package feed
+
+import (
+  "encoding/json"
+  "testing"
+)
+
+func TestV2AuthenticationUnmarshalInvalidData(t *testing.T) {
+  test := []byte(`{}`)
+  var val V2Authentication
+
+  if err := json.Unmarshal(test, &val); err == nil {
+    t.Errorf("got \"%s\", exp error", val)
+  }
+}
+
+func TestV2AuthenticationUnmarshalUnknown(t *testing.T) {
+  test := []byte(`"foo"`)
+  exp := "unknown CVSS v2 authentication: foo"
+  var val V2Authentication
+
+  err := json.Unmarshal(test, &val)
+  if err == nil {
+    t.Errorf("got \"%s\", exp error", val)
+    return
+  }
+
+  if err.Error() != exp {
+    t.Errorf("got \"%s\", exp \"%s\"", err.Error(), exp)
+  }
+}
+
+func TestV2AuthenticationUnmarshalValid(t *testing.T) {
+  tests := []struct {
+    val string
+    exp V2Authentication
+  } {
+    { "\"NONE\"", V2AuthNone },
+    { "\"SINGLE\"", V2AuthSingle },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      var got V2Authentication
+      if err := json.Unmarshal([]byte(test.val), &got); err != nil {
+        t.Error(err)
+        return
+      }
+
+      if got != test.exp {
+        t.Errorf("got \"%s\", exp \"%s\"", got, test.exp)
+      }
+    })
+  }
+}
+
+func TestV2AuthenticationString(t *testing.T) {
+  tests := []struct {
+    val V2Authentication
+    exp string
+  } {
+    { V2AuthNone, "NONE" },
+    { V2AuthSingle, "SINGLE" },
+
+    { V2Authentication(255), "V2Authentication(255)" },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.exp, func(t *testing.T) {
+      got := test.val.String()
+
+      if got != test.exp {
+        t.Errorf("got \"%s\", exp \"%s\"", got, test.exp)
+      }
+    })
+  }
+}