Add tests for subgraph title margin

cypress/integration/rendering/flowchart-v2.spec.js

@@ -874,4 +874,72 @@ end
       });
     });
   });
+  describe('Subgraph title margins', () => {
+    it('Should render subgraphs with title margins set (LR)', () => {
+      imgSnapshotTest(
+        `flowchart LR
+
+          subgraph TOP
+              direction TB
+              subgraph B1
+                  direction RL
+                  i1 -->f1
+              end
+              subgraph B2
+                  direction BT
+                  i2 -->f2
+              end
+          end
+          A --> TOP --> B
+          B1 --> B2
+        `,
+        { flowchart: { subGraphTitleMargin: { top: 10, bottom: 5 } } }
+      );
+    });
+    it('Should render subgraphs with title margins set (TD)', () => {
+      imgSnapshotTest(
+        `flowchart TD
+
+          subgraph TOP
+              direction LR
+              subgraph B1
+                  direction RL
+                  i1 -->f1
+              end
+              subgraph B2
+                  direction BT
+                  i2 -->f2
+              end
+          end
+          A --> TOP --> B
+          B1 --> B2
+        `,
+        { flowchart: { subGraphTitleMargin: { top: 8, bottom: 16 } } }
+      );
+    });
+    it('Should render subgraphs with title margins set (LR) and htmlLabels set to false', () => {
+      imgSnapshotTest(
+        `flowchart LR
+
+          subgraph TOP
+              direction TB
+              subgraph B1
+                  direction RL
+                  i1 -->f1
+              end
+              subgraph B2
+                  direction BT
+                  i2 -->f2
+              end
+          end
+          A --> TOP --> B
+          B1 --> B2
+        `,
+        {
+          htmlLabels: false,
+          flowchart: { htmlLabels: false, subGraphTitleMargin: { top: 10, bottom: 5 } },
+        }
+      );
+    });
+  });
 });