From 2789c067bb4052d4cf46d746bed27759c31c38d7 Mon Sep 17 00:00:00 2001
From: Antonio Barcelos <antonio.barcelos@neo4j.com>
Date: Wed, 10 Nov 2021 13:37:55 +0100
Subject: [PATCH 1/2] teskit-backend: Enabling tests for Result.then

These changes enable the test relate to cosume all records as list in one function call.

The Result implementation in javascript doesn't allow resolve and subscribe at the same result without having strange behaviours. Then, the moment `ResultObserver` subscribes to the `Result` events was moved to the moment someone iteracts with some `ResultObserver` method. This also implies in text which call next before list being skipped.
---
 .../testkit-backend/src/request-handlers.js   | 19 +++++++++++++++++--
 .../testkit-backend/src/result-observer.js    | 14 ++++++++++++++
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/packages/testkit-backend/src/request-handlers.js b/packages/testkit-backend/src/request-handlers.js
index 34b09b206..0b3064c7d 100644
--- a/packages/testkit-backend/src/request-handlers.js
+++ b/packages/testkit-backend/src/request-handlers.js
@@ -125,7 +125,6 @@ export function SessionRun (context, data, wire) {
     .then(_ => {
       const result = session.run(cypher, params, { metadata, timeout })
       const resultObserver = new ResultObserver({ sessionId, result })
-      result.subscribe(resultObserver)
       const id = context.addResultObserver(resultObserver)
       wire.writeResponse('Result', { id })
     })
@@ -169,6 +168,22 @@ export function ResultConsume (context, data, wire) {
     .catch(e => wire.writeError(e))
 }
 
+export function ResultList (context, data, wire) {
+  const { resultId } = data
+
+  const resultObserver = context.getResultObserver(resultId)
+  const result = resultObserver.result
+
+  result
+    .then(({ records }) => {
+      const cypherRecords = records.map(rec => {
+        return { values: Array.from(rec.values()).map(nativeToCypher) }
+      })
+      wire.writeResponse('RecordList', { records: cypherRecords})
+    })
+    .catch(error => wire.writeError(error))
+}
+
 export function SessionReadTransaction (context, data, wire) {
   const { sessionId, txMeta: metadata } = data
   const session = context.getSession(sessionId)
@@ -194,7 +209,6 @@ export function TransactionRun (context, data, wire) {
   }
   const result = tx.tx.run(cypher, params)
   const resultObserver = new ResultObserver({ result })
-  result.subscribe(resultObserver)
   const id = context.addResultObserver(resultObserver)
   wire.writeResponse('Result', { id })
 }
@@ -285,6 +299,7 @@ export function GetFeatures (_context, _params, wire) {
       'Feature:Bolt:4.2',
       'Feature:Bolt:4.3',
       'Feature:Bolt:4.4',
+      'Feature:API:Result.List',
       ...SUPPORTED_TLS
     ]
   })
diff --git a/packages/testkit-backend/src/result-observer.js b/packages/testkit-backend/src/result-observer.js
index c899f55e2..5d5b6d4b2 100644
--- a/packages/testkit-backend/src/result-observer.js
+++ b/packages/testkit-backend/src/result-observer.js
@@ -14,6 +14,7 @@ export default class ResultObserver {
     this.onCompleted = this.onCompleted.bind(this)
     this.onError = this.onError.bind(this)
     this._completitionPromise = null
+    this._subscribed = false
   }
 
   onKeys (keys) {
@@ -39,8 +40,13 @@ export default class ResultObserver {
     this._completitionPromise = null
   }
 
+  get result () {
+    return this._result
+  }
+
   // Returns a promise, only one outstanding next!
   next () {
+    this._subscribe()
     return new Promise((resolve, reject) => {
       this._promise = {
         resolve,
@@ -51,6 +57,7 @@ export default class ResultObserver {
   }
 
   completitionPromise () {
+    this._subscribe()
     return new Promise((resolve, reject) => {
       if (this._summary) {
         resolve(this._summary)
@@ -110,4 +117,11 @@ export default class ResultObserver {
       promise.reject(err)
     }
   }
+
+  _subscribe () {
+    if (!this._subscribed) {
+      this._result.subscribe(this)
+      this._subscribed = true
+    }
+  }
 }

From f06aae666fb2c0e1e1d189233673843a590a7f42 Mon Sep 17 00:00:00 2001
From: Antonio Barcelos <antonio.barcelos@neo4j.com>
Date: Wed, 10 Nov 2021 14:53:15 +0100
Subject: [PATCH 2/2] Skip test which depends on Result.subscribe and then
 Result.then

---
 packages/testkit-backend/src/skipped-tests.js | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/packages/testkit-backend/src/skipped-tests.js b/packages/testkit-backend/src/skipped-tests.js
index d78c49684..778acf6c3 100644
--- a/packages/testkit-backend/src/skipped-tests.js
+++ b/packages/testkit-backend/src/skipped-tests.js
@@ -94,6 +94,18 @@ const skippedTests = [
     ifEquals(
       'neo4j.sessionrun.TestSessionRun.test_partial_iteration'
     )
+  ),
+  skip(
+    'Driver does not support mixing Result.subscribe with Result.then',
+    ifEquals(
+      'stub.iteration.test_result_list.TestResultList.test_tx_run_result_list_pulls_all_records_at_once_next_before_list'
+    ),
+    ifEquals(
+      'stub.iteration.test_result_list.TestResultList.test_tx_func_result_list_pulls_all_records_at_once_next_before_list'
+    ),
+    ifEquals(
+      'stub.iteration.test_result_list.TestResultList.test_session_run_result_list_pulls_all_records_at_once_next_before_list'
+    )
   )
 ]