feat: Add support for scanning GGUF models from OCI registries (#4335)

---------
Signed-off-by: Christopher Phillips <32073428+spiffcs@users.noreply.github.com>
Signed-off-by: Alex Goodman <wagoodman@users.noreply.github.com>
Co-authored-by: Alex Goodman <wagoodman@users.noreply.github.com>

syft/file/mock_resolver.go

@@ -13,16 +13,18 @@ import (
 )
 
 var _ Resolver = (*MockResolver)(nil)
+var _ OCIMediaTypeResolver = (*MockResolver)(nil)
 
 // MockResolver implements the FileResolver interface and is intended for use *only in test code*.
 // It provides an implementation that can resolve local filesystem paths using only a provided discrete list of file
 // paths, which are typically paths to test fixtures.
 type MockResolver struct {
-	locations     []Location
-	metadata      map[Coordinates]Metadata
-	mimeTypeIndex map[string][]Location
-	extension     map[string][]Location
-	basename      map[string][]Location
+	locations      []Location
+	metadata       map[Coordinates]Metadata
+	mimeTypeIndex  map[string][]Location
+	mediaTypeIndex map[string][]Location
+	extension      map[string][]Location
+	basename       map[string][]Location
 }
 
 // NewMockResolverForPaths creates a new MockResolver, where the only resolvable
@@ -72,6 +74,34 @@ func NewMockResolverForPathsWithMetadata(metadata map[Coordinates]Metadata) *Moc
 	}
 }
 
+// NewMockResolverForMediaTypes creates a MockResolver that can resolve files by media type.
+// The mediaTypes map specifies which locations should be returned for each media type.
+func NewMockResolverForMediaTypes(mediaTypes map[string][]Location) *MockResolver {
+	var locations []Location
+	mediaTypeIndex := make(map[string][]Location)
+	extension := make(map[string][]Location)
+	basename := make(map[string][]Location)
+
+	for mediaType, locs := range mediaTypes {
+		mediaTypeIndex[mediaType] = append(mediaTypeIndex[mediaType], locs...)
+		for _, l := range locs {
+			locations = append(locations, l)
+			ext := path.Ext(l.RealPath)
+			extension[ext] = append(extension[ext], l)
+			bn := path.Base(l.RealPath)
+			basename[bn] = append(basename[bn], l)
+		}
+	}
+
+	return &MockResolver{
+		locations:      locations,
+		metadata:       make(map[Coordinates]Metadata),
+		mediaTypeIndex: mediaTypeIndex,
+		extension:      extension,
+		basename:       basename,
+	}
+}
+
 // HasPath indicates if the given path exists in the underlying source.
 func (r MockResolver) HasPath(path string) bool {
 	for _, l := range r.locations {
@@ -189,6 +219,14 @@ func (r MockResolver) FilesByMIMEType(types ...string) ([]Location, error) {
 	return locations, nil
 }
 
+func (r MockResolver) FilesByMediaType(types ...string) ([]Location, error) {
+	var locations []Location
+	for _, ty := range types {
+		locations = append(locations, r.mediaTypeIndex[ty]...)
+	}
+	return locations, nil
+}
+
 func (r MockResolver) FilesByExtension(extensions ...string) ([]Location, error) {
 	var results []Location
 	for _, ext := range extensions {