Add unit tests for the ToPack and PackLLB functions

Add unit tests for the functions in hops/package.go file. These
functions are the backbone for the transformation of hops (i.e.
bunnyfile input) to the final instructions passed to buildkit.

Signed-off-by: Charalampos Mainas <cmainas@nubificus.co.uk>

Author: cmainas

Makefile

@@ -118,7 +118,7 @@ test: unittest
 
 ## unittest Run all unit tests
 .PHONY: unittest
-unittest: test_validate test_parse test_llb test_unikraft test_generic
+unittest: test_validate test_parse test_pack test_llb test_unikraft test_generic
 
 ## test_llb Run unit tests for hops package regarding LLB state creations
 test_llb:
@@ -144,6 +144,12 @@ test_parse:
 	@GOFLAGS=$(TEST_FLAGS) $(GO) test $(TEST_OPTS) ./hops -run TestParse -v
 	@echo " "
 
+## test_pack Run unit tests for hops package regarding packaging from bunnyfile
+test_pack:
+	@echo "Unit testing for bunnyfile-based image building"
+	@GOFLAGS=$(TEST_FLAGS) $(GO) test $(TEST_OPTS) ./hops -run TestPack -v
+	@echo " "
+
 ## test_validate Run unit tests for hops package regarding input validation
 test_validate:
 	@echo "Unit testing in input validation"

hops/package.go

@@ -155,7 +155,7 @@ func ToPack(h *Hops, buildContext string) (*PackInstructions, error) {
 		// 1) The rootfs is empty and we do not have to do anything
 		// 2) The rootfs is a raw type rootfs
 		// The value that will guide us is the From field
-		if h.Rootfs.From != "scratch" {
+		if h.Rootfs.From != "scratch" && h.Rootfs.From != "" {
 			// We have a raw rootfs
 			if !framework.SupportsRootfsType("raw") {
 				return nil, fmt.Errorf("%s does not support raw rootfs type", framework.Name())
@@ -189,13 +189,10 @@ func ToPack(h *Hops, buildContext string) (*PackInstructions, error) {
 	if err != nil {
 		return nil, err
 	}
-	switch framework.GetRootfsType() {
-	case "initrd":
+	if framework.GetRootfsType() == "initrd" {
 		instr.Annots["com.urunc.unikernel.initrd"] = DefaultRootfsPath
-	case "raw":
+	} else if framework.GetRootfsType() == "raw" {
 		instr.Annots["com.urunc.unikernel.mountRootfs"] = "true"
-	default:
-		return nil, fmt.Errorf("Unexpected RootfsType value from framework")
 	}
 
 	// Switch the base to the rootfs's From image