[go-migration] Refactor common context, generate mocks, fix hollow unit tests for supply/finalize

go.mod

@@ -6,9 +6,11 @@ require (
 	github.com/Dynatrace/libbuildpack-dynatrace v1.8.0
 	github.com/cloudfoundry/libbuildpack v0.0.0-20251203175254-7be530ec9fef
 	github.com/cloudfoundry/switchblade v0.9.4
+	github.com/golang/mock v1.6.0
 	github.com/onsi/ginkgo/v2 v2.27.2
 	github.com/onsi/gomega v1.38.2
 	github.com/sclevine/spec v1.4.0
+	go.yaml.in/yaml/v3 v3.0.4
 	gopkg.in/yaml.v2 v2.4.0
 )
 
@@ -42,7 +44,6 @@ require (
 	go.opentelemetry.io/otel v1.32.0 // indirect
 	go.opentelemetry.io/otel/metric v1.32.0 // indirect
 	go.opentelemetry.io/otel/trace v1.32.0 // indirect
-	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/mod v0.30.0 // indirect
 	golang.org/x/net v0.47.0 // indirect
 	golang.org/x/sync v0.18.0 // indirect

src/java/common/context.go

@@ -4,20 +4,49 @@ import (
 	"encoding/json"
 	"fmt"
 	"github.com/cloudfoundry/libbuildpack"
+	"io"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
 )
 
+//go:generate mockgen -source=context.go --destination=../../internal/mocks/mocks.go --package=mocks
+
+type Command interface {
+	Execute(string, io.Writer, io.Writer, string, ...string) error
+}
+
+type Stager interface {
+	LinkDirectoryInDepDir(string, string) error
+	BuildDir() string
+	DepDir() string
+	DepsIdx() string
+	CacheDir() string
+	WriteConfigYml(interface{}) error
+	WriteEnvFile(string, string) error
+	WriteProfileD(string, string) error
+}
+
+type Manifest interface {
+	AllDependencyVersions(string) []string
+	DefaultVersion(string) (libbuildpack.Dependency, error)
+	GetEntry(libbuildpack.Dependency) (*libbuildpack.ManifestEntry, error)
+}
+
+type Installer interface {
+	InstallDependency(libbuildpack.Dependency, string) error
+	InstallDependencyWithStrip(libbuildpack.Dependency, string, int) error
+}
+
 // Context holds shared dependencies for buildpack components
 // Used by containers, frameworks, and JREs to access buildpack infrastructure
 type Context struct {
-	Stager    *libbuildpack.Stager
-	Manifest  *libbuildpack.Manifest
-	Installer *libbuildpack.Installer
+	Stager    Stager
+	Manifest  Manifest
+	Installer Installer
 	Log       *libbuildpack.Logger
-	Command   *libbuildpack.Command
+	Command   Command
 }
 
 // DetermineJavaVersion determines the major Java version from a Java installation