entity/dag: proper base operation for simplified implementation

- reduce boilerplace necessary to implement an operation
- consolidate what an operation is in the core, which in turn pave the way for a generic cache layer mechanism
- avoid the previously complex unmarshalling process
- support operation metadata from the core
- simplified testing

3 files changed, 11 insertions, 8 deletions

diff --git a/bridge/gitlab/export.go b/bridge/gitlab/export.go
index e6587eba..bb83662e 100644
--- a/bridge/gitlab/export.go
+++ b/bridge/gitlab/export.go
@@ -15,6 +15,7 @@ import (
 	"github.com/MichaelMure/git-bug/bug"
 	"github.com/MichaelMure/git-bug/cache"
 	"github.com/MichaelMure/git-bug/entity"
+	"github.com/MichaelMure/git-bug/entity/dag"
 	"github.com/MichaelMure/git-bug/identity"
 )
 
@@ -256,7 +257,7 @@ func (ge *gitlabExporter) exportBug(ctx context.Context, b *cache.BugCache, out
 	labelSet := make(map[string]struct{})
 	for _, op := range snapshot.Operations[1:] {
 		// ignore SetMetadata operations
-		if _, ok := op.(*bug.SetMetadataOperation); ok {
+		if _, ok := op.(dag.OperationDoesntChangeSnapshot); ok {
 			continue
 		}
 
diff --git a/bridge/gitlab/export_test.go b/bridge/gitlab/export_test.go
index cca4c6ca..b48254e6 100644
--- a/bridge/gitlab/export_test.go
+++ b/bridge/gitlab/export_test.go
@@ -11,11 +11,12 @@ import (
 
 	"github.com/xanzy/go-gitlab"
 
+	"github.com/MichaelMure/git-bug/entity/dag"
+
 	"github.com/stretchr/testify/require"
 
 	"github.com/MichaelMure/git-bug/bridge/core"
 	"github.com/MichaelMure/git-bug/bridge/core/auth"
-	"github.com/MichaelMure/git-bug/bug"
 	"github.com/MichaelMure/git-bug/cache"
 	"github.com/MichaelMure/git-bug/repository"
 	"github.com/MichaelMure/git-bug/util/interrupt"
@@ -247,7 +248,7 @@ func TestGitlabPushPull(t *testing.T) {
 			// verify operation have correct metadata
 			for _, op := range tt.bug.Snapshot().Operations {
 				// Check if the originals operations (*not* SetMetadata) are tagged properly
-				if _, ok := op.(*bug.SetMetadataOperation); !ok {
+				if _, ok := op.(dag.OperationDoesntChangeSnapshot); !ok {
 					_, haveIDMetadata := op.GetMetadata(metaKeyGitlabId)
 					require.True(t, haveIDMetadata)
 
@@ -272,7 +273,7 @@ func TestGitlabPushPull(t *testing.T) {
 			require.True(t, ok)
 			require.Equal(t, issueOrigin, target)
 
-			//TODO: maybe more tests to ensure bug final state
+			// TODO: maybe more tests to ensure bug final state
 		})
 	}
 }
diff --git a/bridge/gitlab/import_test.go b/bridge/gitlab/import_test.go
index 676e8749..a4a9ce15 100644
--- a/bridge/gitlab/import_test.go
+++ b/bridge/gitlab/import_test.go
@@ -13,6 +13,7 @@ import (
 	"github.com/MichaelMure/git-bug/bridge/core/auth"
 	"github.com/MichaelMure/git-bug/bug"
 	"github.com/MichaelMure/git-bug/cache"
+	"github.com/MichaelMure/git-bug/entity/dag"
 	"github.com/MichaelMure/git-bug/identity"
 	"github.com/MichaelMure/git-bug/repository"
 	"github.com/MichaelMure/git-bug/util/interrupt"
@@ -49,7 +50,7 @@ func TestGitlabImport(t *testing.T) {
 			name: "simple issue",
 			url:  "https://gitlab.com/git-bug/test/-/issues/1",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "simple issue", "initial comment", nil),
 					bug.NewAddCommentOp(author, 0, "first comment", nil),
 					bug.NewAddCommentOp(author, 0, "second comment", nil),
@@ -60,7 +61,7 @@ func TestGitlabImport(t *testing.T) {
 			name: "empty issue",
 			url:  "https://gitlab.com/git-bug/test/-/issues/2",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "empty issue", "", nil),
 				},
 			},
@@ -69,7 +70,7 @@ func TestGitlabImport(t *testing.T) {
 			name: "complex issue",
 			url:  "https://gitlab.com/git-bug/test/-/issues/3",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "complex issue", "initial comment", nil),
 					bug.NewAddCommentOp(author, 0, "### header\n\n**bold**\n\n_italic_\n\n> with quote\n\n`inline code`\n\n```\nmultiline code\n```\n\n- bulleted\n- list\n\n1. numbered\n1. list\n\n- [ ] task\n- [x] list\n\n@MichaelMure mention\n\n#2 reference issue\n#3 auto-reference issue", nil),
 					bug.NewSetTitleOp(author, 0, "complex issue edited", "complex issue"),
@@ -86,7 +87,7 @@ func TestGitlabImport(t *testing.T) {
 			name: "editions",
 			url:  "https://gitlab.com/git-bug/test/-/issues/4",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "editions", "initial comment edited", nil),
 					bug.NewAddCommentOp(author, 0, "first comment edited", nil),
 				},