feat(git): allow custom merge commit ids

Currently, merge commits can have a git tag, but they cannot have a
custom git commit ID.

This commit allows modifying the default merge commit id.
It also displays all merge commits IDs, which undoes
3ccf027f42

cypress/integration/rendering/gitGraph.spec.js

@@ -74,7 +74,7 @@ describe('Git Graph diagram', () => {
       {}
     );
   });
-  it('7: should render a simple gitgraph with three branches and merge commit', () => {
+  it('7: should render a simple gitgraph with three branches and tagged merge commit', () => {
     imgSnapshotTest(
       `gitGraph
        commit id: "1"
@@ -93,7 +93,7 @@ describe('Git Graph diagram', () => {
        checkout nice_feature
        commit id: "7"
        checkout main
-       merge nice_feature
+       merge nice_feature id: "12345" tag: "my merge commit"
        checkout very_nice_feature
        commit id: "8"
        checkout main

docs/gitgraph.md

@@ -182,6 +182,8 @@ After this we made use of the `checkout` keyword to set the current branch as `m
 After this we merge the `develop` branch onto the current branch `main`, resulting in a merge commit.
 Since the current branch at this point is still `main`, the last two commits are registered against that.
 
+Additionally, you may add a tag to the merge commit, or override the default id: `merge branch id:"1234" tag:"v1.0.0"`
+
 ### Cherry Pick commit from another branch
 Similar to how 'git' allows you to cherry-pick a commit from **another branch** onto the **current** branch, Mermaid also supports this functionality. You can also cherry-pick a commit from another branch using the `cherry-pick` keyword.
 

src/diagrams/git/gitGraphAst.js

@@ -148,8 +148,17 @@ export const branch = function (name, order) {
   }
 };
 
-export const merge = function (otherBranch, tag) {
+/**
+ * Creates a merge commit.
+ *
+ * @param {string} otherBranch - Target branch to merge to.
+ * @param {string} [tag] - Git tag to use on this merge commit.
+ * @param {string} [id] - Git commit id.
+ */
+export const merge = function (otherBranch, tag, id) {
   otherBranch = common.sanitizeText(otherBranch, configApi.getConfig());
+  id = common.sanitizeText(id, configApi.getConfig());
+
   const currentCommit = commits[branches[curBranch]];
   const otherCommit = commits[branches[otherBranch]];
   if (curBranch === otherBranch) {
@@ -219,7 +228,7 @@ export const merge = function (otherBranch, tag) {
   // } else {
   // create merge commit
   const commit = {
-    id: seq + '-' + getId(),
+    id: id || seq + '-' + getId(),
     message: 'merged branch ' + otherBranch + ' into ' + curBranch,
     seq: seq++,
     parents: [head == null ? null : head.id, branches[otherBranch]],

src/diagrams/git/gitGraphParserV2.spec.js

@@ -496,6 +496,76 @@ describe('when parsing a gitGraph', function () {
     ]);
   });
 
+  it('should handle merge ids', function () {
+    const str = `gitGraph:
+      commit
+      branch testBranch
+      checkout testBranch
+      commit
+      checkout main
+      %% Merge Tag and ID
+      merge testBranch tag: "merge-tag" id: "2-222"
+      branch testBranch2
+      checkout testBranch2
+      commit
+      checkout main
+      %% Merge ID and Tag (reverse order)
+      merge testBranch2 id: "4-444" tag: "merge-tag2"
+      branch testBranch3
+      checkout testBranch3
+      commit
+      checkout main
+      %% just Merge ID
+      merge testBranch3 id: "6-666"
+    `;
+
+    parser.parse(str);
+    const commits = parser.yy.getCommits();
+    expect(Object.keys(commits).length).toBe(7);
+    expect(parser.yy.getCurrentBranch()).toBe('main');
+    expect(parser.yy.getDirection()).toBe('LR');
+
+    // The order of these commits is in alphabetical order of IDs
+    const [
+      mainCommit,
+      testBranchCommit,
+      testBranchMerge,
+      testBranch2Commit,
+      testBranch2Merge,
+      testBranch3Commit,
+      testBranch3Merge,
+    ] = Object.values(commits);
+
+    console.log(Object.keys(commits));
+
+    expect(mainCommit.branch).toBe('main');
+    expect(mainCommit.parents).toStrictEqual([]);
+
+    expect(testBranchCommit.branch).toBe('testBranch');
+    expect(testBranchCommit.parents).toStrictEqual([mainCommit.id]);
+
+    expect(testBranchMerge.branch).toBe('main');
+    expect(testBranchMerge.parents).toStrictEqual([mainCommit.id, testBranchCommit.id]);
+    expect(testBranchMerge.tag).toBe('merge-tag');
+    expect(testBranchMerge.id).toBe('2-222');
+
+    expect(testBranch2Merge.branch).toBe('main');
+    expect(testBranch2Merge.parents).toStrictEqual([testBranchMerge.id, testBranch2Commit.id]);
+    expect(testBranch2Merge.tag).toBe('merge-tag2');
+    expect(testBranch2Merge.id).toBe('4-444');
+
+    expect(testBranch3Merge.branch).toBe('main');
+    expect(testBranch3Merge.parents).toStrictEqual([testBranch2Merge.id, testBranch3Commit.id]);
+    expect(testBranch3Merge.id).toBe('6-666');
+
+    expect(parser.yy.getBranchesAsObjArray()).toStrictEqual([
+      { name: 'main' },
+      { name: 'testBranch' },
+      { name: 'testBranch2' },
+      { name: 'testBranch3' },
+    ]);
+  });
+
   it('should throw error when try to branch existing branch: main', function () {
     const str = `gitGraph
     commit

src/diagrams/git/gitGraphRenderer.js

@@ -215,11 +215,7 @@ const drawCommits = (svg, commits, modifyGraph) => {
       const px = 4;
       const py = 2;
       // Draw the commit label
-      if (
+      if (commit.type !== commitType.CHERRY_PICK && gitGraphConfig.showCommitLabel) {
-        commit.type !== commitType.CHERRY_PICK &&
-        commit.type !== commitType.MERGE &&
-        gitGraphConfig.showCommitLabel
-      ) {
         const wrapper = gLabels.append('g');
         const labelBkg = wrapper.insert('rect').attr('class', 'commit-label-bkg');
 

src/diagrams/git/parser/gitGraph.jison

@@ -123,6 +123,9 @@ cherryPickStatement
 mergeStatement
     : MERGE ID {yy.merge($2)}
     | MERGE ID COMMIT_TAG STR {yy.merge($2, $4)}
+    | MERGE ID COMMIT_ID STR {yy.merge($2, '', $4)}
+    | MERGE ID COMMIT_TAG STR COMMIT_ID STR {yy.merge($2, $4, $6)}
+    | MERGE ID COMMIT_ID STR COMMIT_TAG STR {yy.merge($2, $6, $4)}
     ;
 
 commitStatement