parser/metadecoders: Consolidate the metadata decoders

See #5324

parser/metadecoders/format_test.go

@@ -0,0 +1,57 @@
+// Copyright 2018 The Hugo Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package metadecoders
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/gohugoio/hugo/parser/pageparser"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFormatFromString(t *testing.T) {
+	assert := require.New(t)
+	for i, test := range []struct {
+		s      string
+		expect Format
+	}{
+		{"json", JSON},
+		{"yaml", YAML},
+		{"yml", YAML},
+		{"toml", TOML},
+		{"tOMl", TOML},
+		{"org", ORG},
+		{"foo", ""},
+	} {
+		assert.Equal(test.expect, FormatFromString(test.s), fmt.Sprintf("t%d", i))
+	}
+}
+
+func TestFormatFromFrontMatterType(t *testing.T) {
+	assert := require.New(t)
+	for i, test := range []struct {
+		typ    pageparser.ItemType
+		expect Format
+	}{
+		{pageparser.TypeFrontMatterJSON, JSON},
+		{pageparser.TypeFrontMatterTOML, TOML},
+		{pageparser.TypeFrontMatterYAML, YAML},
+		{pageparser.TypeFrontMatterORG, ORG},
+		{pageparser.TypeIgnore, ""},
+	} {
+		assert.Equal(test.expect, FormatFromFrontMatterType(test.typ), fmt.Sprintf("t%d", i))
+	}
+}