Fix unmarshalling bug and add unit test

metric/types.go

@@ -64,11 +64,11 @@ func (t *Type) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	}
 	validTypeStrs := make([]string, 0, len(validTypes))
 	for _, valid := range validTypes {
-		if str == string(valid) {
+		if str == valid.String() {
 			*t = valid
 			return nil
 		}
-		validTypeStrs = append(validTypeStrs, string(valid))
+		validTypeStrs = append(validTypeStrs, valid.String())
 	}
 	return fmt.Errorf("invalid metric type '%s' valid types are: %s",
 		str, strings.Join(validTypeStrs, ", "))

metric/types_test.go

@@ -0,0 +1,57 @@
+// Copyright (c) 2017 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package metric
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	yaml "gopkg.in/yaml.v2"
+)
+
+func TestTypeUnmarshalYAML(t *testing.T) {
+	inputs := []struct {
+		str      string
+		expected Type
+	}{
+		{str: "counter", expected: CounterType},
+		{str: "timer", expected: TimerType},
+		{str: "gauge", expected: GaugeType},
+	}
+	for _, input := range inputs {
+		var typ Type
+		require.NoError(t, yaml.Unmarshal([]byte(input.str), &typ))
+		require.Equal(t, input.expected, typ)
+	}
+}
+
+func TestTypeUnmarshalYAMLErrors(t *testing.T) {
+	inputs := []string{
+		"huh",
+		"blah",
+	}
+	for _, input := range inputs {
+		var typ Type
+		err := yaml.Unmarshal([]byte(input), &typ)
+		require.Error(t, err)
+		require.Equal(t, "invalid metric type '"+input+"' valid types are: counter, timer, gauge", err.Error())
+	}
+}