Implements and tests a SDK roll forward strategy that mimics Microsof…

…t's roll forward policy

[#167848284]

src/dotnetcore/integration/deploy_dotnetcore_app_test.go

@@ -89,8 +89,7 @@ var _ = Describe("CF Dotnet Buildpack", func() {
 
 			})
 
-			XContext("when the sdk is missing", func() {
-				//TODO: https://www.pivotaltracker.com/story/show/167848284
+			Context("when the sdk is missing", func() {
 				BeforeEach(func() {
 					app = ReplaceFileTemplate(filepath.Join(bpDir, "fixtures", "source_2.1_global_json_templated"), "global.json", "sdk_version", "2.1.500")
 				})

src/dotnetcore/supply/supply.go

@@ -9,6 +9,7 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 
 	"github.com/cloudfoundry/dotnet-core-buildpack/src/dotnetcore/config"
@@ -292,13 +293,37 @@ func (s *Supplier) commandsInProjFiles(commands []string) (bool, error) {
 // Turn a semver string into major.minor.x
 // Will turn a.b.c into a.b.x
 // Will not modify strings that don't match a.b.c
-func majorMinorOnly(version string) string {
+func sdkRollForward(version string, versions []string) (string, error) {
+	var featureLine string
+	var highestPatch string
 	parts := strings.SplitN(version, ".", 3)
 	if len(parts) == 3 {
-		parts[2] = "x" // ignore patch version
-		return strings.Join(parts, ".")
+		featureLine = parts[2][:1]
 	}
-	return version
+
+	for _, v := range versions {
+		versionSplit := strings.SplitN(v, ".", 3)
+		if len(versionSplit) == 3 && versionSplit[2][:1] == featureLine {
+			if highestPatch == "" {
+				highestPatch = versionSplit[2][1:]
+			} else {
+				current, err := strconv.Atoi(highestPatch)
+				comp, err := strconv.Atoi(versionSplit[2][1:])
+				if err != nil {
+					return "", err
+				}
+				if current < comp {
+					highestPatch = versionSplit[2][1:]
+				}
+			}
+		}
+	}
+
+	if highestPatch == "" {
+		return "", fmt.Errorf("could not find sdk in same feature line")
+	}
+
+	return fmt.Sprintf("%s.%s.%s%s", parts[0], parts[1], featureLine, highestPatch), nil
 }
 
 func (s *Supplier) pickVersionToInstall() (string, error) {
@@ -327,7 +352,7 @@ func (s *Supplier) pickVersionToInstall() (string, error) {
 			return globalJSONVersion, nil
 		}
 		s.Log.Warning("SDK %s in global.json is not available", globalJSONVersion)
-		installVersion, err := project.FindMatchingVersionWithPreview(majorMinorOnly(globalJSONVersion), allVersions)
+		installVersion, err := sdkRollForward(globalJSONVersion, allVersions)
 		if err == nil {
 			s.Log.Info("falling back to latest version in version line")
 			return installVersion, nil
@@ -408,7 +433,7 @@ func (s *Supplier) suppliedVersion(allVersions []string) (string, error) {
 	}
 	s.Log.Warning("SDK %s in global.json is not available", globalJSONVersion)
 	// TODO: Reevaluate this logic in light of patch lines? https://docs.microsoft.com/en-us/dotnet/core/versions/
-	installVersion, err := project.FindMatchingVersionWithPreview(majorMinorOnly(globalJSONVersion), allVersions)
+	installVersion, err := sdkRollForward(globalJSONVersion, allVersions)
 	if err != nil {
 		return "", nil
 	}

src/dotnetcore/supply/supply_test.go

@@ -336,12 +336,12 @@ var _ = Describe("Supply", func() {
 
 				Context("that is missing, but matches existing version lines", func() {
 					BeforeEach(func() {
-						Expect(ioutil.WriteFile(filepath.Join(buildDir, "global.json"), []byte(`{"sdk": {"version": "1.2.3"}}`), 0644)).To(Succeed())
-						mockManifest.EXPECT().AllDependencyVersions("dotnet-sdk").Return([]string{"1.1.1", "1.2.5", "1.2.6", "1.3.7"})
+						Expect(ioutil.WriteFile(filepath.Join(buildDir, "global.json"), []byte(`{"sdk": {"version": "1.2.301"}}`), 0644)).To(Succeed())
+						mockManifest.EXPECT().AllDependencyVersions("dotnet-sdk").Return([]string{"1.1.113", "1.2.303", "1.2.608", "1.3.709"})
 					})
 
-					It("installs the latest of the same version line", func() {
-						dep := libbuildpack.Dependency{Name: "dotnet-sdk", Version: "1.2.6"}
+					It("installs the latest of the same feature line", func() {
+						dep := libbuildpack.Dependency{Name: "dotnet-sdk", Version: "1.2.303"}
 						mockInstaller.EXPECT().InstallDependency(dep, filepath.Join(depsDir, depsIdx, "dotnet-sdk"))
 
 						Expect(supplier.InstallDotnetSdk()).To(Succeed())
@@ -423,12 +423,12 @@ var _ = Describe("Supply", func() {
 
 				Context("that is missing, but matches existing version lines", func() {
 					BeforeEach(func() {
-						Expect(ioutil.WriteFile(filepath.Join(buildDir, "global.json"), []byte(`{"sdk": {"version": "1.2.3"}}`), 0644)).To(Succeed())
-						mockManifest.EXPECT().AllDependencyVersions("dotnet-sdk").Return([]string{"1.1.1", "1.2.5", "1.2.6", "1.3.7"})
+						Expect(ioutil.WriteFile(filepath.Join(buildDir, "global.json"), []byte(`{"sdk": {"version": "1.2.301"}}`), 0644)).To(Succeed())
+						mockManifest.EXPECT().AllDependencyVersions("dotnet-sdk").Return([]string{"1.1.113", "1.2.303", "1.2.608", "1.3.709"})
 					})
 
-					It("installs the latest of the same version line", func() {
-						dep := libbuildpack.Dependency{Name: "dotnet-sdk", Version: "1.2.6"}
+					It("installs the latest of the same feature line", func() {
+						dep := libbuildpack.Dependency{Name: "dotnet-sdk", Version: "1.2.303"}
 						mockInstaller.EXPECT().InstallDependency(dep, filepath.Join(depsDir, depsIdx, "dotnet-sdk"))
 
 						Expect(supplier.InstallDotnetSdk()).To(Succeed())