chore: migrate tests from tests-ui/ to colocate with source files (#7811)

## Summary

Migrates all unit tests from `tests-ui/` to colocate with their source
files in `src/`, improving discoverability and maintainability.

## Changes

- **What**: Relocated all unit tests to be adjacent to the code they
test, following the `<source>.test.ts` naming convention
- **Config**: Updated `vitest.config.ts` to remove `tests-ui` include
pattern and `@tests-ui` alias
- **Docs**: Moved testing documentation to `docs/testing/` with updated
paths and patterns

## Review Focus

- Migration patterns documented in
`temp/plans/migrate-tests-ui-to-src.md`
- Tests use `@/` path aliases instead of relative imports
- Shared fixtures placed in `__fixtures__/` directories

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-7811-chore-migrate-tests-from-tests-ui-to-colocate-with-source-files-2da6d73d36508147a4cce85365dee614)
by [Unito](https://www.unito.io)

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>

src/workbench/extensions/manager/utils/graphHasMissingNodes.test.ts

@@ -0,0 +1,115 @@
+import { describe, expect, it } from 'vitest'
+
+import type {
+  LGraph,
+  LGraphNode,
+  Subgraph
+} from '@/lib/litegraph/src/litegraph'
+import {
+  collectMissingNodes,
+  graphHasMissingNodes
+} from '@/workbench/extensions/manager/utils/graphHasMissingNodes'
+import type { NodeDefLookup } from '@/workbench/extensions/manager/utils/graphHasMissingNodes'
+import type { ComfyNodeDefImpl } from '@/stores/nodeDefStore'
+
+type NodeDefs = NodeDefLookup
+
+let nodeIdCounter = 0
+const mockNodeDef = {} as ComfyNodeDefImpl
+
+const createGraph = (nodes: LGraphNode[] = []): LGraph => {
+  return { nodes } as Partial<LGraph> as LGraph
+}
+
+const createSubgraph = (nodes: LGraphNode[]): Subgraph => {
+  return { nodes } as Partial<Subgraph> as Subgraph
+}
+
+const createNode = (
+  type?: string,
+  subgraphNodes?: LGraphNode[]
+): LGraphNode => {
+  return {
+    id: nodeIdCounter++,
+    type,
+    isSubgraphNode: subgraphNodes ? () => true : undefined,
+    subgraph: subgraphNodes ? createSubgraph(subgraphNodes) : undefined
+  } as unknown as LGraphNode
+}
+
+describe('graphHasMissingNodes', () => {
+  it('returns false when graph is null', () => {
+    expect(graphHasMissingNodes(null, {})).toBe(false)
+  })
+
+  it('returns false when graph is undefined', () => {
+    expect(graphHasMissingNodes(undefined, {})).toBe(false)
+  })
+
+  it('returns false when graph has no nodes', () => {
+    expect(graphHasMissingNodes(createGraph(), {})).toBe(false)
+  })
+
+  it('returns false when every node has a definition', () => {
+    const graph = createGraph([createNode('FooNode'), createNode('BarNode')])
+    const nodeDefs: NodeDefs = {
+      FooNode: mockNodeDef,
+      BarNode: mockNodeDef
+    }
+
+    expect(graphHasMissingNodes(graph, nodeDefs)).toBe(false)
+  })
+
+  it('returns true when at least one node is missing', () => {
+    const graph = createGraph([
+      createNode('FooNode'),
+      createNode('MissingNode')
+    ])
+    const nodeDefs: NodeDefs = {
+      FooNode: mockNodeDef
+    }
+
+    expect(graphHasMissingNodes(graph, nodeDefs)).toBe(true)
+  })
+
+  it('checks nodes nested in subgraphs', () => {
+    const graph = createGraph([
+      createNode('ContainerNode', [createNode('InnerMissing')])
+    ])
+    const nodeDefs: NodeDefs = {
+      ContainerNode: mockNodeDef
+    }
+
+    const missingNodes = collectMissingNodes(graph, nodeDefs)
+    expect(missingNodes).toHaveLength(1)
+    expect(missingNodes[0]?.type).toBe('InnerMissing')
+  })
+
+  it('ignores nodes without a type', () => {
+    const graph = createGraph([
+      createNode(undefined),
+      createNode(null as unknown as string)
+    ])
+
+    expect(graphHasMissingNodes(graph, {})).toBe(false)
+  })
+
+  it('traverses deeply nested subgraphs', () => {
+    const deepGraph = createGraph([
+      createNode('Layer1', [
+        createNode('Layer2', [
+          createNode('Layer3', [createNode('MissingDeep')])
+        ])
+      ])
+    ])
+    const nodeDefs: NodeDefs = {
+      Layer1: mockNodeDef,
+      Layer2: mockNodeDef,
+      Layer3: mockNodeDef
+    }
+
+    const missingNodes = collectMissingNodes(deepGraph, nodeDefs)
+    expect(missingNodes).toHaveLength(1)
+    expect(missingNodes[0]?.type).toBe('MissingDeep')
+  })
+})