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, 14 insertions, 12 deletions

diff --git a/bridge/github/export.go b/bridge/github/export.go
index 35d456c2..5164fcab 100644
--- a/bridge/github/export.go
+++ b/bridge/github/export.go
@@ -20,6 +20,7 @@ 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"
 )
 
@@ -288,7 +289,7 @@ func (ge *githubExporter) exportBug(ctx context.Context, b *cache.BugCache, out
 
 	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/github/export_test.go b/bridge/github/export_test.go
index 94664853..93cc47c0 100644
--- a/bridge/github/export_test.go
+++ b/bridge/github/export_test.go
@@ -15,8 +15,8 @@ import (
 
 	"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/entity/dag"
 	"github.com/MichaelMure/git-bug/repository"
 	"github.com/MichaelMure/git-bug/util/interrupt"
 )
@@ -245,7 +245,7 @@ func TestGithubPushPull(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(metaKeyGithubId)
 					require.True(t, haveIDMetadata)
 
diff --git a/bridge/github/import_test.go b/bridge/github/import_test.go
index df4989a4..f1c863ac 100644
--- a/bridge/github/import_test.go
+++ b/bridge/github/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"
@@ -44,7 +45,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "simple issue",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/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),
@@ -55,7 +56,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "empty issue",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/2",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "empty issue", "", nil),
 				},
 			},
@@ -64,7 +65,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "complex issue",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/3",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "complex issue", "initial comment", nil),
 					bug.NewLabelChangeOperation(author, 0, []bug.Label{"bug"}, []bug.Label{}),
 					bug.NewLabelChangeOperation(author, 0, []bug.Label{"duplicate"}, []bug.Label{}),
@@ -81,7 +82,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "editions",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/4",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "editions", "initial comment edited", nil),
 					bug.NewEditCommentOp(author, 0, "", "erased then edited again", nil),
 					bug.NewAddCommentOp(author, 0, "first comment", nil),
@@ -93,7 +94,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "comment deletion",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/5",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "comment deletion", "", nil),
 				},
 			},
@@ -102,7 +103,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "edition deletion",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/6",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "edition deletion", "initial comment", nil),
 					bug.NewEditCommentOp(author, 0, "", "initial comment edited again", nil),
 					bug.NewAddCommentOp(author, 0, "first comment", nil),
@@ -114,7 +115,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "hidden comment",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/7",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "hidden comment", "initial comment", nil),
 					bug.NewAddCommentOp(author, 0, "first comment", nil),
 				},
@@ -124,7 +125,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "transfered issue",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/8",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "transfered issue", "", nil),
 				},
 			},
@@ -133,7 +134,7 @@ func TestGithubImporter(t *testing.T) {
 			name: "unicode control characters",
 			url:  "https://github.com/MichaelMure/git-bug-test-github-bridge/issues/10",
 			bug: &bug.Snapshot{
-				Operations: []bug.Operation{
+				Operations: []dag.Operation{
 					bug.NewCreateOp(author, 0, "unicode control characters", "u0000: \nu0001: \nu0002: \nu0003: \nu0004: \nu0005: \nu0006: \nu0007: \nu0008: \nu0009: \t\nu0010: \nu0011: \nu0012: \nu0013: \nu0014: \nu0015: \nu0016: \nu0017: \nu0018: \nu0019:", nil),
 				},
 			},