use shared libnodejs function to find applications

build.go

@@ -1,18 +1,17 @@
 package nodestart
 
 import (
-	"os"
-
+	"github.com/paketo-buildpacks/libnodejs"
 	"github.com/paketo-buildpacks/libreload-packit"
 	"github.com/paketo-buildpacks/packit/v2"
 	"github.com/paketo-buildpacks/packit/v2/scribe"
 )
 
-func Build(applicationFinder ApplicationFinder, logger scribe.Emitter, reloader Reloader) packit.BuildFunc {
+func Build(logger scribe.Emitter, reloader Reloader) packit.BuildFunc {
 	return func(context packit.BuildContext) (packit.BuildResult, error) {
 		logger.Title("%s %s", context.BuildpackInfo.Name, context.BuildpackInfo.Version)
 
-		file, err := applicationFinder.Find(context.WorkingDir, os.Getenv("BP_LAUNCHPOINT"), os.Getenv("BP_NODE_PROJECT_PATH"))
+		file, err := libnodejs.FindNodeApplication(context.WorkingDir)
 		if err != nil {
 			return packit.BuildResult{}, err
 		}

build_test.go

@@ -3,6 +3,9 @@ package nodestart_test
 import (
 	"bytes"
 	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
 	"testing"
 
 	"github.com/paketo-buildpacks/libreload-packit"
@@ -24,8 +27,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		cnbDir     string
 		buffer     *bytes.Buffer
 
-		applicationFinder *fakes.ApplicationFinder
-		reloader          *fakes.Reloader
+		reloader *fakes.Reloader
 
 		buildContext packit.BuildContext
 		build        packit.BuildFunc
@@ -36,8 +38,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		cnbDir = t.TempDir()
 		workingDir = t.TempDir()
 
-		applicationFinder = &fakes.ApplicationFinder{}
-		applicationFinder.FindCall.Returns.String = "server.js"
+		Expect(os.WriteFile(filepath.Join(workingDir, "server.js"), nil, 0600)).To(Succeed())
 
 		reloader = &fakes.Reloader{}
 
@@ -57,7 +58,7 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 			},
 			Layers: packit.Layers{Path: layersDir},
 		}
-		build = nodestart.Build(applicationFinder, logger, reloader)
+		build = nodestart.Build(logger, reloader)
 	})
 
 	it("returns a result that provides a node start command", func() {
@@ -82,8 +83,6 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 			},
 		}))
 
-		Expect(applicationFinder.FindCall.Receives.WorkingDir).To(Equal(workingDir))
-
 		Expect(buffer.String()).To(ContainSubstring("Some Buildpack some-version"))
 		Expect(buffer.String()).To(ContainSubstring("Assigning launch processes"))
 		Expect(buffer.String()).To(ContainSubstring("node server.js"))
@@ -137,12 +136,12 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 	context("failure cases", func() {
 		context("when the application finding fails", func() {
 			it.Before(func() {
-				applicationFinder.FindCall.Returns.Error = errors.New("failed to find application")
+				Expect(os.Remove(filepath.Join(workingDir, "server.js"))).To(Succeed())
 			})
 
 			it("returns an error", func() {
 				_, err := build(buildContext)
-				Expect(err).To(MatchError("failed to find application"))
+				Expect(err).To(MatchError(fmt.Errorf("could not find app in %s: expected one of server.js | app.js | main.js | index.js", workingDir)))
 			})
 		})
 

detect.go

@@ -17,9 +17,9 @@ type Reloader libreload.Reloader
 
 //go:generate faux --interface Reloader --output fakes/reloader.go
 
-func Detect(applicationFinder ApplicationFinder, reloader Reloader) packit.DetectFunc {
+func Detect(reloader Reloader) packit.DetectFunc {
 	return func(context packit.DetectContext) (packit.DetectResult, error) {
-		_, err := applicationFinder.Find(context.WorkingDir, os.Getenv("BP_LAUNCHPOINT"), os.Getenv("BP_NODE_PROJECT_PATH"))
+		_, err := libnodejs.FindNodeApplication(context.WorkingDir)
 		if err != nil {
 			return packit.DetectResult{}, err
 		}

detect_test.go

@@ -2,6 +2,7 @@ package nodestart_test
 
 import (
 	"errors"
+	"fmt"
 	"os"
 	"path/filepath"
 	"testing"
@@ -18,8 +19,7 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 	var (
 		Expect = NewWithT(t).Expect
 
-		applicationFinder *fakes.ApplicationFinder
-		reloader          *fakes.Reloader
+		reloader *fakes.Reloader
 
 		detect     packit.DetectFunc
 		workingDir string
@@ -28,12 +28,9 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 	it.Before(func() {
 		workingDir = t.TempDir()
 
-		applicationFinder = &fakes.ApplicationFinder{}
-		applicationFinder.FindCall.Returns.String = "./src/server.js"
-
 		reloader = &fakes.Reloader{}
 
-		detect = nodestart.Detect(applicationFinder, reloader)
+		detect = nodestart.Detect(reloader)
 	})
 
 	context("when an application is detected in the working dir", func() {
@@ -59,10 +56,6 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 					},
 				},
 			}))
-
-			Expect(applicationFinder.FindCall.Receives.WorkingDir).To(Equal(workingDir))
-			Expect(applicationFinder.FindCall.Receives.Launchpoint).To(Equal("./src/server.js"))
-			Expect(applicationFinder.FindCall.Receives.ProjectPath).To(Equal("./src"))
 		})
 
 		context("when live reload is enabled", func() {
@@ -98,7 +91,7 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 			t.Setenv("BP_NODE_PROJECT_PATH", "./src")
 			Expect(os.MkdirAll(filepath.Join(workingDir, "src"), os.ModePerm)).To(Succeed())
 			Expect(os.WriteFile(filepath.Join(workingDir, "src", "package.json"), []byte(`{}`), 0600)).To(Succeed())
-
+			Expect(os.WriteFile(filepath.Join(workingDir, "src", "server.js"), nil, 0600)).To(Succeed())
 		})
 
 		it("requires node_modules", func() {
@@ -125,15 +118,11 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 
 	context("failure cases", func() {
 		context("when the application finder fails", func() {
-			it.Before(func() {
-				applicationFinder.FindCall.Returns.Error = errors.New("application finder failed")
-			})
-
 			it("fails with helpful error", func() {
 				_, err := detect(packit.DetectContext{
 					WorkingDir: workingDir,
 				})
-				Expect(err).To(MatchError("application finder failed"))
+				Expect(err).To(MatchError(fmt.Errorf("could not find app in %s: expected one of server.js | app.js | main.js | index.js", workingDir)))
 			})
 		})
 
@@ -156,6 +145,7 @@ func testDetect(t *testing.T, context spec.G, it spec.S) {
 
 		context("when the reloader returns an error", func() {
 			it.Before(func() {
+				Expect(os.WriteFile(filepath.Join(workingDir, "server.js"), nil, 0600)).To(Succeed())
 				reloader.ShouldEnableLiveReloadCall.Returns.Error = errors.New("reloader error")
 			})
 

go.sum

@@ -2487,6 +2487,8 @@ github.com/otiai10/curr v1.0.0/go.mod h1:LskTG5wDwr8Rs+nNQ+1LlxRjAtTZZjtJW4rMXl6
 github.com/otiai10/mint v1.3.0/go.mod h1:F5AjcsTsWUqX+Na9fpHb52P8pcRX2CI6A3ctIT91xUo=
 github.com/otiai10/mint v1.3.1/go.mod h1:/yxELlJQ0ufhjUwhshSj+wFjZ78CnZ48/1wtmBH1OTc=
 github.com/pact-foundation/pact-go v1.0.4/go.mod h1:uExwJY4kCzNPcHRj+hCR/HBbOOIwwtUjcrb0b5/5kLM=
+github.com/paketo-buildpacks/libnodejs v0.0.2 h1:3pPWg0b2uzaPkKNqVRT3dCGJ6XheuMZpJw8mBp/bYLc=
+github.com/paketo-buildpacks/libnodejs v0.0.2/go.mod h1:D69iwG2Uu9Y0VHOrs2xDk9Oy91qMo9j+gLaRwP2jINw=
 github.com/paketo-buildpacks/libnodejs v0.1.0 h1:MaZXwK5QOn2pwrVya2i2PogQDo8n8pFefCvZIjGHo2U=
 github.com/paketo-buildpacks/libnodejs v0.1.0/go.mod h1:6zYvjp6d0mw2Sw/3ITF1CTk7dLQigpI37QGoG2IFeRE=
 github.com/paketo-buildpacks/libreload-packit v0.0.1 h1:K1HhNAqBSzRpefwGOcvdchZwyeNTgNJL9SC7V4paYt8=

init_test.go

@@ -11,6 +11,5 @@ func TestUnitNodeStart(t *testing.T) {
 	suite := spec.New("node-start", spec.Report(report.Terminal{}), spec.Sequential())
 	suite("Build", testBuild)
 	suite("Detect", testDetect)
-	suite("ApplicationFinder", testNodeApplicationFinder)
 	suite.Run(t)
 }