feat: Ensure proper detection for flowcharts

packages/mermaid/src/diagram-api/detectType.ts

@@ -46,7 +46,9 @@ export const detectType = function (text: string, config?: MermaidConfig): strin
     }
   }
 
-  throw new UnknownDiagramError(`No diagram type detected for text: ${text}`);
+  throw new UnknownDiagramError(
+    `No diagram type detected matching given configuration for text: ${text}`
+  );
 };
 
 export const registerLazyLoadedDiagrams = (...diagrams: ExternalDiagramDefinition[]) => {

packages/mermaid/src/diagram-api/diagram-orchestration.spec.ts

@@ -41,5 +41,42 @@ describe('diagram-orchestration', () => {
         expect(detectType(text)).toBe(expected);
       }
     );
+
+    it('should detect proper flowchart type based on config', () => {
+      // graph & dagre-d3 => flowchart
+      expect(detectType('graph TD; A-->B')).toBe('flowchart');
+      // graph & dagre-d3 => flowchart
+      expect(detectType('graph TD; A-->B', { flowchart: { defaultRenderer: 'dagre-d3' } })).toBe(
+        'flowchart'
+      );
+      // flowchart & dagre-d3 => error
+      expect(() =>
+        detectType('flowchart TD; A-->B', { flowchart: { defaultRenderer: 'dagre-d3' } })
+      ).toThrowErrorMatchingInlineSnapshot(
+        '"No diagram type detected matching given configuration for text: flowchart TD; A-->B"'
+      );
+
+      // graph & dagre-wrapper => flowchart-v2
+      expect(
+        detectType('graph TD; A-->B', { flowchart: { defaultRenderer: 'dagre-wrapper' } })
+      ).toBe('flowchart-v2');
+      // flowchart ==> flowchart-v2
+      expect(detectType('flowchart TD; A-->B')).toBe('flowchart-v2');
+      // flowchart && dagre-wrapper ==> flowchart-v2
+      expect(
+        detectType('flowchart TD; A-->B', { flowchart: { defaultRenderer: 'dagre-wrapper' } })
+      ).toBe('flowchart-v2');
+      // flowchart && elk ==> flowchart-elk
+      expect(detectType('flowchart TD; A-->B', { flowchart: { defaultRenderer: 'elk' } })).toBe(
+        'flowchart-elk'
+      );
+    });
+
+    it('should not detect flowchart if pie contains flowchart', () => {
+      expect(
+        detectType(`pie title: "flowchart"
+      flowchart: 1 "pie" pie: 2 "pie"`)
+      ).toBe('pie');
+    });
   });
 });

packages/mermaid/src/diagram-api/diagram-orchestration.ts

@@ -68,10 +68,8 @@ export const addDiagrams = () => {
     requirement,
     sequence,
     flowchartElk,
-    // TODO @knsv: Should v2 come before flowchart?
-    // This will fail few unit tests as they expect graph to be detected as flowchart, but it is detected as flowchart-v2.
-    flowchart,
     flowchartV2,
+    flowchart,
     mindmap,
     timeline,
     git,

packages/mermaid/src/diagram-api/diagramAPI.spec.ts

@@ -20,8 +20,8 @@ describe('DiagramAPI', () => {
 
   it('should handle diagram registrations', () => {
     expect(() => getDiagram('loki')).toThrow();
-    expect(() => detectType('loki diagram')).toThrow(
+    expect(() => detectType('loki diagram')).toThrowErrorMatchingInlineSnapshot(
-      'No diagram type detected for text: loki diagram'
+      '"No diagram type detected matching given configuration for text: loki diagram"'
     );
     const detector: DiagramDetector = (str: string) => {
       return str.match('loki') !== null;

packages/mermaid/src/diagram.spec.ts

@@ -61,8 +61,8 @@ Expecting 'TXT', got 'NEWLINE'"
   });
 
   test('should throw the right error for unregistered diagrams', async () => {
-    await expect(getDiagramFromText('thor TD; A-->B')).rejects.toThrowError(
+    await expect(getDiagramFromText('thor TD; A-->B')).rejects.toThrowErrorMatchingInlineSnapshot(
-      'No diagram type detected for text: thor TD; A-->B'
+      '"No diagram type detected matching given configuration for text: thor TD; A-->B"'
     );
   });
 });

packages/mermaid/src/diagrams/flowchart/flowDetector-v2.ts

@@ -4,15 +4,15 @@ import type { ExternalDiagramDefinition } from '../../diagram-api/types';
 const id = 'flowchart-v2';
 
 const detector: DiagramDetector = (txt, config) => {
-  if (config?.flowchart?.defaultRenderer === 'dagre-d3') {
+  if (
-    return false;
+    config?.flowchart?.defaultRenderer === 'dagre-d3' ||
-  }
+    config?.flowchart?.defaultRenderer === 'elk'
-  if (config?.flowchart?.defaultRenderer === 'elk') {
+  ) {
     return false;
   }
 
   // If we have configured to use dagre-wrapper then we should return true in this function for graph code thus making it use the new flowchart diagram
-  if (txt.match(/^\s*graph/) !== null) {
+  if (txt.match(/^\s*graph/) !== null && config?.flowchart?.defaultRenderer === 'dagre-wrapper') {
     return true;
   }
   return txt.match(/^\s*flowchart/) !== null;

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

@@ -5,10 +5,10 @@ const id = 'flowchart';
 const detector: DiagramDetector = (txt, config) => {
   // If we have conferred to only use new flow charts this function should always return false
   // as in not signalling true for a legacy flowchart
-  if (config?.flowchart?.defaultRenderer === 'dagre-wrapper') {
+  if (
-    return false;
+    config?.flowchart?.defaultRenderer === 'dagre-wrapper' ||
-  }
+    config?.flowchart?.defaultRenderer === 'elk'
-  if (config?.flowchart?.defaultRenderer === 'elk') {
+  ) {
     return false;
   }
   return txt.match(/^\s*graph/) !== null;

packages/mermaid/src/mermaid.ts

@@ -12,6 +12,7 @@ import type { ParseErrorFunction } from './Diagram';
 import { isDetailedError } from './utils';
 import type { DetailedError } from './utils';
 import { ExternalDiagramDefinition } from './diagram-api/types';
+import { UnknownDiagramError } from './errors';
 
 export type {
   MermaidConfig,
@@ -20,6 +21,7 @@ export type {
   ParseErrorFunction,
   RenderResult,
   ParseOptions,
+  UnknownDiagramError,
 };
 
 export interface RunOptions {

packages/mermaid/src/mermaidAPI.spec.ts

@@ -678,7 +678,7 @@ describe('mermaidAPI', () => {
       await expect(
         mermaidAPI.parse('this is not a mermaid diagram definition')
       ).rejects.toThrowErrorMatchingInlineSnapshot(
-        '"No diagram type detected for text: this is not a mermaid diagram definition"'
+        '"No diagram type detected matching given configuration for text: this is not a mermaid diagram definition"'
       );
     });
     it('returns false for invalid definition with silent option', async () => {