Move runtime.txt logic into python-compat-cnb

[#163886457]

Co-authored-by: Chhavi Kankaria <[email protected]>

.gitignore

@@ -1,3 +1,5 @@
 .DS_Store
 .idea
 .bin
+python-cnb_*
+python-cnb.tgz

cmd/detect/main.go

@@ -19,6 +19,11 @@ func main() {
 	context, err := detect.DefaultDetect()
 	if err != nil {
 		_, _ = fmt.Fprintf(os.Stderr, "failed to create a default detection context: %s", err)
+		os.Exit(100)
+	}
+
+	if err := context.BuildPlan.Init(); err != nil {
+		_, _ = fmt.Fprintf(os.Stderr, "Failed to initialize Build Plan: %s\n", err)
 		os.Exit(101)
 	}
 
@@ -31,26 +36,14 @@ func main() {
 }
 
 func runDetect(context detect.Detect) (int, error) {
-	runtimePath := filepath.Join(context.Application.Root, "runtime.txt")
-	exists, err := helper.FileExists(runtimePath)
-	if err != nil {
-		return detect.FailStatusCode, err
-	}
-
-	var version string
-	if exists {
-		version, err = readRuntimeTxtVersion(runtimePath)
-		if err != nil {
-			return detect.FailStatusCode, err
-		}
-	}
 
 	buildpackYAMLPath := filepath.Join(context.Application.Root, "buildpack.yml")
-	exists, err = helper.FileExists(buildpackYAMLPath)
+	exists, err := helper.FileExists(buildpackYAMLPath)
 	if err != nil {
 		return detect.FailStatusCode, err
 	}
 
+	version := context.BuildPlan[python.Dependency].Version
 	if exists {
 		version, err = readBuildpackYamlVersion(buildpackYAMLPath)
 		if err != nil {
@@ -66,11 +59,6 @@ func runDetect(context detect.Detect) (int, error) {
 	})
 }
 
-func readRuntimeTxtVersion(runtimePath string) (string, error) {
-	buf, err := ioutil.ReadFile(runtimePath)
-	return string(buf), err
-}
-
 func readBuildpackYamlVersion(buildpackYAMLPath string) (string, error) {
 	buf, err := ioutil.ReadFile(buildpackYAMLPath)
 	if err != nil {

cmd/detect/main_test.go

@@ -42,7 +42,7 @@ func testDetect(t *testing.T, when spec.G, it spec.S) {
 
 	when("testing versions", func() {
 
-		when("there is no runtime.txt or buildpack.yml", func() {
+		when("there is no buildpack.yml", func() {
 			it("shouldn't set the version in the buildplan", func() {
 				code, err := runDetect(factory.Detect)
 				Expect(err).NotTo(HaveOccurred())
@@ -57,28 +57,7 @@ func testDetect(t *testing.T, when spec.G, it spec.S) {
 			})
 		})
 
-		when("there is a runtime.txt but no buildpack.yml", func() {
-			const version string = "1.2.3"
-
-			it.Before(func() {
-				Expect(helper.WriteFile(filepath.Join(factory.Detect.Application.Root, "runtime.txt"), 0666, version)).To(Succeed())
-			})
-
-			it("should pass with the requested version of python", func() {
-				code, err := runDetect(factory.Detect)
-				Expect(err).NotTo(HaveOccurred())
-				Expect(code).To(Equal(detect.PassStatusCode))
-
-				Expect(factory.Output).To(Equal(buildplan.BuildPlan{
-					python.Dependency: buildplan.Dependency{
-						Version:  version,
-						Metadata: buildplan.Metadata{"build": true, "launch": true},
-					},
-				}))
-			})
-		})
-
-		when("there is a buildpack.yml but no runtime.txt", func() {
+		when("there is a buildpack.yml", func() {
 			const version string = "1.2.3"
 
 			it.Before(func() {
@@ -100,14 +79,17 @@ func testDetect(t *testing.T, when spec.G, it spec.S) {
 			})
 		})
 
-		when("there is a buildpack.yml and a runtime.txt", func() {
+		when("there is a is an existing version from the build plan and a buildpack.yml", func() {
 			const buildpackYAMLVersion string = "1.2.3"
-			const runtimeVersion string = "4.5.6"
+			const existingVersion string = "4.5.6"
 
 			it.Before(func() {
+				factory.AddBuildPlan(python.Dependency, buildplan.Dependency{
+					Version: existingVersion,
+				})
+
 				buildpackYAMLString := fmt.Sprintf("python:\n  version: %s", buildpackYAMLVersion)
 				Expect(helper.WriteFile(filepath.Join(factory.Detect.Application.Root, "buildpack.yml"), 0666, buildpackYAMLString)).To(Succeed())
-				Expect(helper.WriteFile(filepath.Join(factory.Detect.Application.Root, "runtime.txt"), 0666, runtimeVersion)).To(Succeed())
 			})
 
 			it("should pass with the requested version of python defined in buildpack.yml", func() {