refactor: extract helpers from _removeDuplicateLinks and add integration tests (#10332)

browser_tests/tests/graph.spec.ts

@@ -23,4 +23,85 @@ test.describe('Graph', { tag: ['@smoke', '@canvas'] }, () => {
     await comfyPage.workflow.loadWorkflow('links/bad_link')
     await expect.poll(() => comfyPage.toast.getVisibleToastCount()).toBe(2)
   })
+
+  // Regression: duplicate links with shifted target_slot (widget-to-input
+  // conversion) caused the wrong link to survive during deduplication.
+  // Switch(CFG) node 120 connects to both KSamplerAdvanced 85 and 86 (2 links).
+  // Links 257 and 276 shared the same tuple (origin=120 → target=85 slot=5).
+  // Node 85's input.link was 276 (valid), but the bug kept 257 (stale) and
+  // removed 276, breaking the cfg connection on KSamplerAdvanced 85.
+  // Ref: https://github.com/Comfy-Org/ComfyUI_frontend/issues/10291
+  test('Deduplicates links without breaking connections on slot-drift workflow', async ({
+    comfyPage
+  }) => {
+    await comfyPage.workflow.loadWorkflow('links/duplicate_links_slot_drift')
+
+    const result = await comfyPage.page.evaluate(() => {
+      const graph = window.app!.graph!
+
+      const subgraph = graph.subgraphs.values().next().value
+      if (!subgraph) return { error: 'No subgraph found' }
+
+      // Node 120 = Switch (CFG), connects to both KSamplerAdvanced 85 and 86
+      const switchCfg = subgraph.getNodeById(120)
+      const ksampler85 = subgraph.getNodeById(85)
+      const ksampler86 = subgraph.getNodeById(86)
+      if (!switchCfg || !ksampler85 || !ksampler86)
+        return { error: 'Required nodes not found' }
+
+      // Find cfg inputs by name (slot indices shift due to widget-to-input)
+      const cfgInput85 = ksampler85.inputs.find(
+        (i: { name: string }) => i.name === 'cfg'
+      )
+      const cfgInput86 = ksampler86.inputs.find(
+        (i: { name: string }) => i.name === 'cfg'
+      )
+      const cfg85Linked = cfgInput85?.link != null
+      const cfg86Linked = cfgInput86?.link != null
+
+      // Verify the surviving links exist in the subgraph link map
+      const cfg85LinkValid =
+        cfg85Linked && subgraph.links.has(cfgInput85!.link!)
+      const cfg86LinkValid =
+        cfg86Linked && subgraph.links.has(cfgInput86!.link!)
+
+      // Switch(CFG) output should have exactly 2 links (one to each KSampler)
+      const switchOutputLinkCount = switchCfg.outputs[0]?.links?.length ?? 0
+
+      // Count links from Switch(CFG) to node 85 cfg (should be 1, not 2)
+      let cfgLinkToNode85Count = 0
+      for (const link of subgraph.links.values()) {
+        if (link.origin_id === 120 && link.target_id === 85)
+          cfgLinkToNode85Count++
+      }
+
+      return {
+        cfg85Linked,
+        cfg86Linked,
+        cfg85LinkValid,
+        cfg86LinkValid,
+        cfg85LinkId: cfgInput85?.link ?? null,
+        cfg86LinkId: cfgInput86?.link ?? null,
+        switchOutputLinkIds: [...(switchCfg.outputs[0]?.links ?? [])],
+        switchOutputLinkCount,
+        cfgLinkToNode85Count
+      }
+    })
+
+    expect(result).not.toHaveProperty('error')
+    // Both KSamplerAdvanced nodes must have their cfg input connected
+    expect(result.cfg85Linked).toBe(true)
+    expect(result.cfg86Linked).toBe(true)
+    // Links must exist in the subgraph link map
+    expect(result.cfg85LinkValid).toBe(true)
+    expect(result.cfg86LinkValid).toBe(true)
+    // Switch(CFG) output has exactly 2 links (one per KSamplerAdvanced)
+    expect(result.switchOutputLinkCount).toBe(2)
+    // Only 1 link from Switch(CFG) to node 85 (duplicate removed)
+    expect(result.cfgLinkToNode85Count).toBe(1)
+    // Output link IDs must match the input link IDs (source/target integrity)
+    expect(result.switchOutputLinkIds).toEqual(
+      expect.arrayContaining([result.cfg85LinkId, result.cfg86LinkId])
+    )
+  })
 })