Add IsVirtual() to compile spec

pkg/compiler/compiler.go

@@ -522,9 +522,9 @@ func (cs *LuetCompiler) compileWithImage(image, buildertaggedImage, packageImage
 	p CompilationSpec, generateArtifact bool) (Artifact, error) {
 
 	// If it is a virtual, check if we have to generate an empty artifact or not.
-	if generateArtifact && p.EmptyPackage() && !p.HasImageSource() {
+	if generateArtifact && p.IsVirtual() {
 		return cs.genArtifact(p, CompilerBackendOptions{}, CompilerBackendOptions{}, concurrency, keepPermissions)
-	} else if p.EmptyPackage() && !p.HasImageSource() {
+	} else if p.IsVirtual() {
 		return &PackageArtifact{}, nil
 	}
 

pkg/compiler/interface.go

@@ -186,6 +186,7 @@ type CompilationSpec interface {
 	EmptyPackage() bool
 	UnpackedPackage() bool
 	HasImageSource() bool
+	IsVirtual() bool
 }
 
 type CompilationSpecs interface {

pkg/compiler/spec.go

@@ -114,12 +114,12 @@ func NewLuetCompilationSpec(b []byte, p pkg.Package) (CompilationSpec, error) {
 	spec.Package = p.(*pkg.DefaultPackage)
 	return &spec, nil
 }
-func (a *LuetCompilationSpec) GetSourceAssertion() solver.PackagesAssertions {
-	return a.SourceAssertion
+func (cs *LuetCompilationSpec) GetSourceAssertion() solver.PackagesAssertions {
+	return cs.SourceAssertion
 }
 
-func (a *LuetCompilationSpec) SetSourceAssertion(as solver.PackagesAssertions) {
-	a.SourceAssertion = as
+func (cs *LuetCompilationSpec) SetSourceAssertion(as solver.PackagesAssertions) {
+	cs.SourceAssertion = as
 }
 func (cs *LuetCompilationSpec) GetPackage() pkg.Package {
 	return cs.Package
@@ -157,6 +157,12 @@ func (cs *LuetCompilationSpec) GetRetrieve() []string {
 	return cs.Retrieve
 }
 
+// IsVirtual returns true if the spec is virtual.
+// A spec is virtual if the package is empty, and it has no image source to unpack from.
+func (cs *LuetCompilationSpec) IsVirtual() bool {
+	return cs.EmptyPackage() && !cs.HasImageSource()
+}
+
 func (cs *LuetCompilationSpec) GetSeedImage() string {
 	return cs.Seed
 }
@@ -199,8 +205,11 @@ func (cs *LuetCompilationSpec) UnpackedPackage() bool {
 	return unpack
 }
 
+// HasImageSource returns true when the compilation spec has an image source.
+// a compilation spec has an image source when it depends on other packages or have a source image
+// explictly supplied
 func (cs *LuetCompilationSpec) HasImageSource() bool {
-	return len(cs.GetPackage().GetRequires()) != 0 || cs.GetImage() != ""
+	return (cs.Package != nil && len(cs.GetPackage().GetRequires()) != 0) || cs.GetImage() != ""
 }
 
 func (cs *LuetCompilationSpec) CopyRetrieves(dest string) error {

pkg/compiler/spec_test.go

@@ -51,6 +51,26 @@ var _ = Describe("Spec", func() {
 			Expect(newSpec2.All()).To(Equal([]CompilationSpec{testSpec3}))
 
 		})
+		Context("virtuals", func() {
+			When("is empty", func() {
+				It("is virtual", func() {
+					spec := &LuetCompilationSpec{}
+					Expect(spec.IsVirtual()).To(BeTrue())
+				})
+			})
+			When("has defined steps", func() {
+				It("is not a virtual", func() {
+					spec := &LuetCompilationSpec{Steps: []string{"foo"}}
+					Expect(spec.IsVirtual()).To(BeFalse())
+				})
+			})
+			When("has defined image", func() {
+				It("is not a virtual", func() {
+					spec := &LuetCompilationSpec{Image: "foo"}
+					Expect(spec.IsVirtual()).To(BeFalse())
+				})
+			})
+		})
 	})
 
 	Context("Simple package build definition", func() {