container: add tests for resolver

Add checks for the new `container.Resolver`, including the failure
case.

internal/container/resolver_test.go

@@ -0,0 +1,84 @@
+package container_test
+
+import (
+	"fmt"
+	"sort"
+	"testing"
+	"time"
+
+	"github.com/osbuild/osbuild-composer/internal/common"
+	"github.com/osbuild/osbuild-composer/internal/container"
+	"github.com/stretchr/testify/assert"
+)
+
+type lessCompare func(i, j int) bool
+
+func makeSpecSorter(specs []container.Spec) lessCompare {
+	return func(i, j int) bool {
+		return specs[i].Digest < specs[j].Digest
+	}
+}
+
+func TestResolver(t *testing.T) {
+
+	registry := NewTestRegistry()
+	defer registry.Close()
+
+	repo := registry.AddRepo("library/osbuild")
+	ref := registry.GetRef("library/osbuild")
+
+	refs := make([]string, 10)
+	for i := 0; i < len(refs); i++ {
+		checksum := repo.AddImage(
+			[]Blob{NewDataBlobFromBase64(rootLayer)},
+			[]string{"amd64", "ppc64le"},
+			fmt.Sprintf("image %d", i),
+			time.Time{})
+
+		tag := fmt.Sprintf("%d", i)
+		repo.AddTag(checksum, tag)
+		refs[i] = fmt.Sprintf("%s:%s", ref, tag)
+	}
+
+	resolver := container.NewResolver("amd64")
+
+	for _, r := range refs {
+		resolver.Add(r, "", common.BoolToPtr(false))
+	}
+
+	have, err := resolver.Finish()
+	assert.NoError(t, err)
+	assert.NotNil(t, have)
+
+	assert.Len(t, have, len(refs))
+
+	want := make([]container.Spec, len(refs))
+	for i, r := range refs {
+		spec, err := registry.Resolve(r, "amd64")
+		assert.NoError(t, err)
+		want[i] = spec
+	}
+
+	sort.Slice(have, makeSpecSorter(have))
+	sort.Slice(want, makeSpecSorter(want))
+
+	assert.ElementsMatch(t, have, want)
+}
+
+func TestResolverFail(t *testing.T) {
+	resolver := container.NewResolver("amd64")
+
+	resolver.Add("invalid-reference@${IMAGE_DIGEST}", "", common.BoolToPtr(false))
+
+	specs, err := resolver.Finish()
+	assert.Error(t, err)
+	assert.Len(t, specs, 0)
+
+	registry := NewTestRegistry()
+	defer registry.Close()
+
+	resolver.Add(registry.GetRef("repo"), "", common.BoolToPtr(false))
+	specs, err = resolver.Finish()
+	assert.Error(t, err)
+	assert.Len(t, specs, 0)
+}