Use draft.Planner from packit directly

See paketo-buildpacks/cpython#327 for context

Author: joshuatcasey

build.go

@@ -7,23 +7,17 @@ import (
 
 	"github.com/paketo-buildpacks/packit/v2"
 	"github.com/paketo-buildpacks/packit/v2/chronos"
+	"github.com/paketo-buildpacks/packit/v2/draft"
 	"github.com/paketo-buildpacks/packit/v2/fs"
 	"github.com/paketo-buildpacks/packit/v2/sbom"
 	"github.com/paketo-buildpacks/packit/v2/scribe"
 )
 
-//go:generate faux --interface EntryResolver --output fakes/entry_resolver.go
 //go:generate faux --interface InstallProcess --output fakes/install_process.go
 //go:generate faux --interface SitePackagesProcess --output fakes/site_packages_process.go
 //go:generate faux --interface VenvDirLocator --output fakes/venv_dir_locator.go
 //go:generate faux --interface SBOMGenerator --output fakes/sbom_generator.go
 
-// EntryResolver defines the interface for picking the most relevant entry from
-// the Buildpack Plan entries.
-type EntryResolver interface {
-	MergeLayerTypes(name string, entries []packit.BuildpackPlanEntry) (launch, build bool)
-}
-
 // SitePackagesProcess defines the interface for determining the site-packages path.
 type SitePackagesProcess interface {
 	Execute(layerPath string) (sitePackagesPath string, err error)
@@ -51,7 +45,6 @@ type SBOMGenerator interface {
 // packages layer. It also makes use of a cache layer to reuse the pipenv
 // cache.
 func Build(
-	entryResolver EntryResolver,
 	installProcess InstallProcess,
 	siteProcess SitePackagesProcess,
 	venvDirLocator VenvDirLocator,
@@ -72,7 +65,8 @@ func Build(
 			return packit.BuildResult{}, err
 		}
 
-		packagesLayer.Launch, packagesLayer.Build = entryResolver.MergeLayerTypes(SitePackages, context.Plan.Entries)
+		planner := draft.NewPlanner()
+		packagesLayer.Launch, packagesLayer.Build = planner.MergeLayerTypes(SitePackages, context.Plan.Entries)
 		packagesLayer.Cache = packagesLayer.Launch || packagesLayer.Build
 		cacheLayer.Cache = true
 

build_test.go

@@ -30,7 +30,6 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		buffer     *bytes.Buffer
 		logEmitter scribe.Emitter
 
-		entryResolver       *fakes.EntryResolver
 		installProcess      *fakes.InstallProcess
 		sitePackagesProcess *fakes.SitePackagesProcess
 		venvDirLocator      *fakes.VenvDirLocator
@@ -51,7 +50,6 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		cnbDir, err = os.MkdirTemp("", "cnb")
 		Expect(err).NotTo(HaveOccurred())
 
-		entryResolver = &fakes.EntryResolver{}
 		installProcess = &fakes.InstallProcess{}
 		sitePackagesProcess = &fakes.SitePackagesProcess{}
 		venvDirLocator = &fakes.VenvDirLocator{}
@@ -65,7 +63,6 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		logEmitter = scribe.NewEmitter(buffer)
 
 		build = pipenvinstall.Build(
-			entryResolver,
 			installProcess,
 			sitePackagesProcess,
 			venvDirLocator,
@@ -139,11 +136,6 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 		Expect(installProcess.ExecuteCall.Receives.TargetLayer.Path).To(Equal(filepath.Join(layersDir, "packages")))
 		Expect(installProcess.ExecuteCall.Receives.CacheLayer.Path).To(Equal(filepath.Join(layersDir, "cache")))
 
-		Expect(entryResolver.MergeLayerTypesCall.Receives.Name).To(Equal("site-packages"))
-		Expect(entryResolver.MergeLayerTypesCall.Receives.Entries).To(Equal([]packit.BuildpackPlanEntry{
-			{Name: "site-packages"},
-		}))
-
 		Expect(buffer.String()).To(ContainSubstring("Some Buildpack some-version"))
 		Expect(buffer.String()).To(ContainSubstring("Executing build process"))
 
@@ -152,8 +144,10 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 
 	context("site-packages required at build and launch", func() {
 		it.Before(func() {
-			entryResolver.MergeLayerTypesCall.Returns.Launch = true
-			entryResolver.MergeLayerTypesCall.Returns.Build = true
+			buildContext.Plan.Entries[0].Metadata = map[string]interface{}{
+				"launch": true,
+				"build":  true,
+			}
 		})
 
 		it("layer's build, launch, cache flags must be set", func() {
@@ -181,8 +175,10 @@ func testBuild(t *testing.T, context spec.G, it spec.S) {
 				}
 				return nil
 			}
-			entryResolver.MergeLayerTypesCall.Returns.Launch = true
-			entryResolver.MergeLayerTypesCall.Returns.Build = true
+			buildContext.Plan.Entries[0].Metadata = map[string]interface{}{
+				"launch": true,
+				"build":  true,
+			}
 		})
 
 		it("result should include a cache layer", func() {

fakes/entry_resolver.go

@@ -5,7 +5,6 @@ import (
 
 	"github.com/paketo-buildpacks/packit/v2"
 	"github.com/paketo-buildpacks/packit/v2/chronos"
-	"github.com/paketo-buildpacks/packit/v2/draft"
 	"github.com/paketo-buildpacks/packit/v2/pexec"
 	"github.com/paketo-buildpacks/packit/v2/sbom"
 	"github.com/paketo-buildpacks/packit/v2/scribe"
@@ -27,7 +26,6 @@ func main() {
 			pipenvinstall.NewPipfileLockParser(),
 		),
 		pipenvinstall.Build(
-			draft.NewPlanner(),
 			pipenvinstall.NewPipenvInstallProcess(pexec.NewExecutable("pipenv"), logger),
 			pipenvinstall.NewSiteProcess(pexec.NewExecutable("python")),
 			pipenvinstall.NewVenvLocator(),