Refactored version directory names

3.0 and 2.0 do not work, there are multiple versions and anything with a period in it sucks from my point of view, v2 and v3 feel much better from a DX perspective.

datamodel/low/v3/server_test.go

@@ -0,0 +1,60 @@
+// Copyright 2022 Princess B33f Heavy Industries / Dave Shanley
+// SPDX-License-Identifier: MIT
+
+package v3
+
+import (
+	"github.com/pb33f/libopenapi/datamodel/low"
+	"github.com/pb33f/libopenapi/index"
+	"github.com/stretchr/testify/assert"
+	"gopkg.in/yaml.v3"
+	"testing"
+)
+
+func TestServer_Build(t *testing.T) {
+
+	yml := `url: https://pb33f.io
+description: high quality software for developers.
+variables:
+  var1: 
+    default: hello
+    description: a var
+    enum: [one, two]`
+
+	var idxNode yaml.Node
+	_ = yaml.Unmarshal([]byte(yml), &idxNode)
+	idx := index.NewSpecIndex(&idxNode)
+
+	var n Server
+	err := low.BuildModel(&idxNode, &n)
+	assert.NoError(t, err)
+
+	err = n.Build(idxNode.Content[0], idx)
+	assert.NoError(t, err)
+	assert.Equal(t, "https://pb33f.io", n.URL.Value)
+	assert.Equal(t, "high quality software for developers.", n.Description.Value)
+	assert.Equal(t, "hello", n.FindVariable("var1").Value.Default.Value)
+	assert.Equal(t, "a var", n.FindVariable("var1").Value.Description.Value)
+
+}
+
+func TestServer_Build_NoVars(t *testing.T) {
+
+	yml := `url: https://pb33f.io
+description: high quality software for developers.`
+
+	var idxNode yaml.Node
+	_ = yaml.Unmarshal([]byte(yml), &idxNode)
+	idx := index.NewSpecIndex(&idxNode)
+
+	var n Server
+	err := low.BuildModel(&idxNode, &n)
+	assert.NoError(t, err)
+
+	err = n.Build(idxNode.Content[0], idx)
+	assert.NoError(t, err)
+	assert.Equal(t, "https://pb33f.io", n.URL.Value)
+	assert.Equal(t, "high quality software for developers.", n.Description.Value)
+	assert.Len(t, n.Variables.Value, 0)
+
+}