7 files changed, 270 insertions, 60 deletions
diff --git a/internal/feed/feed.go b/internal/feed/feed.go
index affa5d2..3a6e695 100644
--- a/internal/feed/feed.go
+++ b/internal/feed/feed.go
@@ -1,15 +1,5 @@
 package feed
 
-import (
-  "encoding/json"
-  "fmt"
-)
-
-const (
-  CvssVersion31 = iota  // CVSS version 3.1
-  CvssVersion20 // CVSS version 2.0
-)
-
 // TODO: parse cpe, cve id
 
 // CVE metadata
@@ -126,58 +116,10 @@ type ItemConfigurations struct {
   Nodes []ConfigurationNode `json:"nodes"`
 }
 
-// CVSS version.
-type CvssV3Version int
-
-// Unmarshal CVSS version from JSON.
-func (me *CvssV3Version) 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 "3.1":
-    *me = CvssVersion31
-  default:
-    // return error
-    return fmt.Errorf("unknown CVSS V3 version: %s", s)
-  }
-
-  // return success
-  return nil
-}
-
-// CVSS V2 version.
-type CvssV2Version int
-
-// Unmarshal CVSS version from JSON.
-func (me *CvssV2Version) 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 "2.0":
-    *me = CvssVersion20
-  default:
-    // return error
-    return fmt.Errorf("unknown CVSS V2 version: %s", s)
-  }
-
-  // return success
-  return nil
-}
-
 // CVSS V3
 type CvssV3 struct {
   // CVSS V3 version
-  Version CvssV3Version `json:"version"`
+  Version V3Version `json:"version"`
 
   // CVSS V3 vector string (FIXME: add custom type)
   VectorString string `json:"vectorString"`
@@ -220,7 +162,7 @@ type BaseMetricV3 struct {
 // CVSS V2
 type CvssV2 struct {
   // CVSS V2 version
-  Version CvssV2Version `json:"version"`
+  Version V2Version `json:"version"`
 
   // CVSS V3 vector string (FIXME: add custom type)
   VectorString string `json:"vectorString"`
diff --git a/internal/feed/v2version.go b/internal/feed/v2version.go
new file mode 100644
index 0000000..76e6134
--- /dev/null
+++ b/internal/feed/v2version.go
@@ -0,0 +1,36 @@
+package feed
+
+//go:generate stringer -linecomment -type=V2Version
+
+import (
+  "encoding/json"
+  "fmt"
+)
+
+// CVSS v2 version
+type V2Version byte
+
+const (
+  V20 V2Version = iota // 2.0
+)
+
+// Unmarshal CVSS V2 version from JSON.
+func (me *V2Version) 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 "2.0":
+    *me = V20
+  default:
+    // return error
+    return fmt.Errorf("unknown CVSS version: %s", s)
+  }
+
+  // return success
+  return nil
+}
diff --git a/internal/feed/v2version_string.go b/internal/feed/v2version_string.go
new file mode 100644
index 0000000..6b13870
--- /dev/null
+++ b/internal/feed/v2version_string.go
@@ -0,0 +1,23 @@
+// Code generated by "stringer -linecomment -type=V2Version"; 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[V20-0]
+}
+
+const _V2Version_name = "2.0"
+
+var _V2Version_index = [...]uint8{0, 3}
+
+func (i V2Version) String() string {
+	if i >= V2Version(len(_V2Version_index)-1) {
+		return "V2Version(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _V2Version_name[_V2Version_index[i]:_V2Version_index[i+1]]
+}
diff --git a/internal/feed/v2version_test.go b/internal/feed/v2version_test.go
new file mode 100644
index 0000000..3b9b029
--- /dev/null
+++ b/internal/feed/v2version_test.go
@@ -0,0 +1,75 @@
+package feed
+
+import (
+  "encoding/json"
+  "testing"
+)
+
+func TestV2VersionUnmarshalInvalidData(t *testing.T) {
+  test := []byte(`{}`)
+  var val V2Version
+
+  if err := json.Unmarshal(test, &val); err == nil {
+    t.Errorf("got \"%s\", exp error", val)
+  }
+}
+
+func TestV2VersionUnmarshalUnknown(t *testing.T) {
+  test := []byte(`"foo"`)
+  exp := "unknown CVSS version: foo"
+  var val V2Version
+
+  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 TestV2VersionUnmarshalValid(t *testing.T) {
+  tests := []struct {
+    val string
+    exp V2Version
+  } {
+    { "\"2.0\"", V20 },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      var got V2Version
+      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 TestV2VersionString(t *testing.T) {
+  tests := []struct {
+    val V2Version
+    exp string
+  } {
+    { V20, "2.0" },
+
+    { V2Version(255), "V2Version(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)
+      }
+    })
+  }
+}
diff --git a/internal/feed/v3version.go b/internal/feed/v3version.go
new file mode 100644
index 0000000..537fecc
--- /dev/null
+++ b/internal/feed/v3version.go
@@ -0,0 +1,36 @@
+package feed
+
+//go:generate stringer -linecomment -type=V3Version
+
+import (
+  "encoding/json"
+  "fmt"
+)
+
+// CVSS v3 version
+type V3Version byte
+
+const (
+  V31 V3Version = iota // 3.1
+)
+
+// Unmarshal CVSS V3 version from JSON.
+func (me *V3Version) 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 "3.1":
+    *me = V31
+  default:
+    // return error
+    return fmt.Errorf("unknown CVSS version: %s", s)
+  }
+
+  // return success
+  return nil
+}
diff --git a/internal/feed/v3version_string.go b/internal/feed/v3version_string.go
new file mode 100644
index 0000000..9de58a7
--- /dev/null
+++ b/internal/feed/v3version_string.go
@@ -0,0 +1,23 @@
+// Code generated by "stringer -linecomment -type=V3Version"; 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[V31-0]
+}
+
+const _V3Version_name = "3.1"
+
+var _V3Version_index = [...]uint8{0, 3}
+
+func (i V3Version) String() string {
+	if i >= V3Version(len(_V3Version_index)-1) {
+		return "V3Version(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _V3Version_name[_V3Version_index[i]:_V3Version_index[i+1]]
+}
diff --git a/internal/feed/v3version_test.go b/internal/feed/v3version_test.go
new file mode 100644
index 0000000..89cc6ed
--- /dev/null
+++ b/internal/feed/v3version_test.go
@@ -0,0 +1,75 @@
+package feed
+
+import (
+  "encoding/json"
+  "testing"
+)
+
+func TestV3VersionUnmarshalInvalidData(t *testing.T) {
+  test := []byte(`{}`)
+  var val V3Version
+
+  if err := json.Unmarshal(test, &val); err == nil {
+    t.Errorf("got \"%s\", exp error", val)
+  }
+}
+
+func TestV3VersionUnmarshalUnknown(t *testing.T) {
+  test := []byte(`"foo"`)
+  exp := "unknown CVSS version: foo"
+  var val V3Version
+
+  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 TestV3VersionUnmarshalValid(t *testing.T) {
+  tests := []struct {
+    val string
+    exp V3Version
+  } {
+    { "\"3.1\"", V31 },
+  }
+
+  for _, test := range(tests) {
+    t.Run(test.val, func(t *testing.T) {
+      var got V3Version
+      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 TestV3VersionString(t *testing.T) {
+  tests := []struct {
+    val V3Version
+    exp string
+  } {
+    { V31, "3.1" },
+
+    { V3Version(255), "V3Version(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)
+      }
+    })
+  }
+}