fix: error mermaid.parse on invalid shapes

Currently, invalid shapes cause an error when rendering, but not when
parsing. This confuses the Mermaid Live Editor, e.g. by not showing the
error message.

Instead, I've added an `isValidShape()` that validates if the shape is
valid at parse time. This only checks shapes using the new extended
shapes syntax. Currenlty, using `A(-this is an ellipse node-)` is broken
(see mermaid-js#5976) and also causes an invalid shape error at render time, but
I've ignored it in this PR, so it will continue pass at parse-time
(we have unit tests checking ellipse parsing).

See: mermaid-js#5976

.changeset/thick-elephants-search.md

@@ -0,0 +1,5 @@
+---
+'mermaid': patch
+---
+
+fix: error `mermaid.parse` on an invalid shape, so that it matches the errors thrown by `mermaid.render`

packages/mermaid/src/diagrams/flowchart/flowDb.ts

@@ -2,6 +2,7 @@ import { select } from 'd3';
 import utils, { getEdgeId } from '../../utils.js';
 import { getConfig, defaultConfig } from '../../diagram-api/diagramAPI.js';
 import common from '../common/common.js';
+import { isValidShape, type ShapeID } from '../../rendering-util/rendering-elements/shapes.js';
 import type { Node, Edge } from '../../rendering-util/types.js';
 import { log } from '../../logger.js';
 import * as yaml from 'js-yaml';
@@ -140,14 +141,15 @@ export const addVertex = function (
     }
     // console.log('yamlData', yamlData);
     const doc = yaml.load(yamlData, { schema: yaml.JSON_SCHEMA }) as NodeMetaData;
-    if (doc.shape && (doc.shape !== doc.shape.toLowerCase() || doc.shape.includes('_'))) {
-      throw new Error(`No such shape: ${doc.shape}. Shape names should be lowercase.`);
-    }
-
-    // console.log('yamlData doc', doc);
-    if (doc?.shape) {
+    if (doc.shape) {
+      if (doc.shape !== doc.shape.toLowerCase() || doc.shape.includes('_')) {
+        throw new Error(`No such shape: ${doc.shape}. Shape names should be lowercase.`);
+      } else if (!isValidShape(doc.shape)) {
+        throw new Error(`No such shape: ${doc.shape}.`);
+      }
       vertex.type = doc?.shape;
     }
+
     if (doc?.label) {
       vertex.text = doc?.label;
     }
@@ -823,7 +825,7 @@ export const lex = {
   firstGraph,
 };
 
-const getTypeFromVertex = (vertex: FlowVertex) => {
+const getTypeFromVertex = (vertex: FlowVertex): ShapeID => {
   if (vertex.img) {
     return 'imageSquare';
   }
@@ -845,6 +847,9 @@ const getTypeFromVertex = (vertex: FlowVertex) => {
       return 'squareRect';
     case 'round':
       return 'roundedRect';
+    case 'ellipse':
+      // @ts-expect-error -- Ellipses are broken, see https://github.com/mermaid-js/mermaid/issues/5976
+      return 'ellipse';
     default:
       return vertex.type;
   }

packages/mermaid/src/diagrams/flowchart/parser/flow-node-data.spec.js

@@ -197,6 +197,21 @@ describe('when parsing directions', function () {
     expect(data4Layout.nodes[0].shape).toEqual('squareRect');
     expect(data4Layout.nodes[0].label).toEqual('This is }');
   });
+  it('should error on non-existent shape', function () {
+    expect(() => {
+      flow.parser.parse(`flowchart TB
+      A@{ shape: this-shape-does-not-exist }
+      `);
+    }).toThrow('No such shape: this-shape-does-not-exist.');
+  });
+  it('should error on internal-only shape', function () {
+    expect(() => {
+      // this shape does exist, but it's only supposed to be for internal/backwards compatibility use
+      flow.parser.parse(`flowchart TB
+      A@{ shape: rect_left_inv_arrow }
+      `);
+    }).toThrow('No such shape: rect_left_inv_arrow. Shape names should be lowercase.');
+  });
   it('Diamond shapes should work as usual', function () {
     const res = flow.parser.parse(`flowchart TB
       A{This is a label}

packages/mermaid/src/diagrams/flowchart/types.ts

@@ -1,3 +1,5 @@
+import type { ShapeID } from '../../rendering-util/rendering-elements/shapes.js';
+
 /**
  * Valid `type` args to `yy.addVertex` taken from
  * `packages/mermaid/src/diagrams/flowchart/parser/flow.jison`
@@ -33,7 +35,7 @@ export interface FlowVertex {
   props?: any;
   styles: string[];
   text?: string;
-  type?: string;
+  type?: ShapeID | FlowVertexTypeParam;
   icon?: string;
   form?: string;
   pos?: 't' | 'b';

packages/mermaid/src/rendering-util/rendering-elements/nodes.ts

@@ -27,7 +27,7 @@ export async function insertNode(
     }
   }
 
-  const shapeHandler = shapes[(node.shape ?? 'undefined') as keyof typeof shapes];
+  const shapeHandler = node.shape ? shapes[node.shape] : undefined;
 
   if (!shapeHandler) {
     throw new Error(`No such shape: ${node.shape}. Please check your syntax.`);

packages/mermaid/src/rendering-util/rendering-elements/shapes.ts

@@ -491,4 +491,8 @@ const generateShapeMap = () => {
 
 export const shapes = generateShapeMap();
 
+export function isValidShape(shape: string): shape is ShapeID {
+  return shape in shapes;
+}
+
 export type ShapeID = keyof typeof shapes;

packages/mermaid/src/rendering-util/types.ts

@@ -1,5 +1,6 @@
 export type MarkdownWordType = 'normal' | 'strong' | 'em';
 import type { MermaidConfig } from '../config.type.js';
+import type { ShapeID } from './rendering-elements/shapes.js';
 export interface MarkdownWord {
   content: string;
   type: MarkdownWordType;
@@ -37,7 +38,7 @@ export interface Node {
   linkTarget?: string;
   tooltip?: string;
   padding?: number; //REMOVE?, use from LayoutData.config - Keep, this could be shape specific
-  shape?: string;
+  shape?: ShapeID;
   isGroup: boolean;
   width?: number;
   height?: number;