fix(gatsby): single page node manifest accuracy (#33642)

* expect the manifest has the correct foundPageBy
* ensure foundPageBy is accurate when there's only 1 relevant page

integration-tests/node-manifest/__tests__/create-node-manifest.test.js

@@ -53,13 +53,15 @@ describe(`Node Manifest API in "gatsby ${gatsbyCommandName}"`, () => {
 
     expect(manifestFileContents.node.id).toBe(`1`)
     expect(manifestFileContents.page.path).toBe(`/one`)
+    expect(manifestFileContents.foundPageBy).toBe(`ownerNodeId`)
   })
 
   it(`Creates an accurate node manifest when ownerNodeId isn't present but there's a matching "id" in pageContext`, async () => {
     const manifestFileContents = await getManifestContents(2)
 
     expect(manifestFileContents.node.id).toBe(`2`)
     expect(manifestFileContents.page.path).toBe(`/two`)
+    expect(manifestFileContents.foundPageBy).toBe(`context.id`)
   })
 
   if (gatsbyCommandName === `build`) {
@@ -74,6 +76,7 @@ describe(`Node Manifest API in "gatsby ${gatsbyCommandName}"`, () => {
           manifestFileContents.page.path
         )
       ).toBe(true)
+      expect(manifestFileContents.foundPageBy).toBe(`queryTracking`)
     })
 
     // this doesn't work in gatsby develop since page-data.json files aren't written out
@@ -93,12 +96,14 @@ describe(`Node Manifest API in "gatsby ${gatsbyCommandName}"`, () => {
 
     expect(manifestFileContents.node.id).toBe(`4`)
     expect(manifestFileContents.page.path).toBe(null)
+    expect(manifestFileContents.foundPageBy).toBe(`none`)
   })
 
   it(`Creates a Node manifest for filesystem routes`, async () => {
     const manifestFileContents = await getManifestContents(`filesystem-1`)
 
     expect(manifestFileContents.node.id).toBe(`filesystem-1`)
     expect(manifestFileContents.page.path).toBe(`/filesystem-1/`)
+    expect(manifestFileContents.foundPageBy).toBe(`filesystem-route-api`)
   })
 })

packages/gatsby/src/utils/node-manifest.ts

@@ -70,9 +70,7 @@ async function findPageOwnedByNodeId({ nodeId }: { nodeId: string }): Promise<{
 
   let foundPageBy: FoundPageBy = pagePath ? `queryTracking` : `none`
 
-  // but if we have more than one page where this node shows up
-  // we need to try to be more specific
-  if (pagePathSetOrMap && pagePathSetOrMap.size > 1) {
+  if (pagePathSetOrMap) {
     let ownerPagePath: string | undefined
     let foundOwnerNodeId = false