Fix subgraph issue

src/diagrams/flowchart/parser/flow.spec.js

@@ -22,6 +22,17 @@ describe('when parsing ', function () {
     expect(edges[0].text).toBe('')
   })
 
+  it('should handle subgraph with tab indentation', function () {
+    const res = flow.parser.parse('graph TB\nsubgraph One\n\ta1-->a2\nend')
+    const subgraphs = flow.parser.yy.getSubGraphs()
+    expect(subgraphs.length).toBe(1)
+    const subgraph = subgraphs[0]
+    expect(subgraph.nodes.length).toBe(2)
+    expect(subgraph.nodes[0]).toBe('a1')
+    expect(subgraph.nodes[1]).toBe('a2')
+    expect(subgraph.title).toBe('One')
+  })
+
   it('should handle angle bracket ' > ' as direction LR', function () {
     const res = flow.parser.parse('graph >;A-->B;')