feat: add node version segment

segment.go

@@ -50,6 +50,8 @@ const (
 	Spotify SegmentType = "spotify"
 	//ShellInfo writes which shell we're currently in
 	ShellInfo SegmentType = "shell"
+	//NVM writes which node version is currently active using nvm
+	NVM SegmentType = "nvm"
 	//Powerline writes it Powerline style
 	Powerline SegmentStyle = "powerline"
 	//Plain writes it without ornaments
@@ -80,6 +82,7 @@ func (segment *Segment) mapSegmentWithWriter(env environmentInfo) *properties {
 		Battery:   &batt{},
 		Spotify:   &spotify{},
 		ShellInfo: &shell{},
+		NVM:       &nvm{},
 	}
 	if writer, ok := functions[segment.Type]; ok {
 		props := &properties{

segment_nvm.go

@@ -0,0 +1,24 @@
+package main
+
+type nvm struct {
+	props       *properties
+	env         environmentInfo
+	nodeVersion string
+}
+
+func (n *nvm) string() string {
+	return n.nodeVersion
+}
+
+func (n *nvm) init(props *properties, env environmentInfo) {
+	n.props = props
+	n.env = env
+}
+
+func (n *nvm) enabled() bool {
+	if !n.env.hasCommand("node") {
+		return false
+	}
+	n.nodeVersion = n.env.runCommand("node", "--version")
+	return true
+}

segment_nvm_test.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type nvmArgs struct {
+	enabled     bool
+	nodeVersion string
+}
+
+func bootStrapNVMTest(args *nvmArgs) *nvm {
+	env := new(MockedEnvironment)
+	env.On("hasCommand", "node").Return(args.enabled)
+	env.On("runCommand", "node", []string{"--version"}).Return(args.nodeVersion)
+	nvm := &nvm{
+		env: env,
+	}
+	return nvm
+}
+
+func TestNVMWriterDisabled(t *testing.T) {
+	args := &nvmArgs{
+		enabled: false,
+	}
+	nvm := bootStrapNVMTest(args)
+	assert.False(t, nvm.enabled(), "the nvm command is not available")
+}
+
+func TestNVMWriterEnabled(t *testing.T) {
+	expected := "1.14"
+	args := &nvmArgs{
+		enabled:     true,
+		nodeVersion: expected,
+	}
+	nvm := bootStrapNVMTest(args)
+	assert.True(t, nvm.enabled(), "the nvm command is available")
+	assert.Equal(t, expected, nvm.string(), "the nvm command is available")
+}