fix(changedAttributes): initial value of property which are supposed to be null return a value when the record is in flight (#480)

* test: add tests of attributes initially null to proove regression

* fix: changedAttributes return the correct value until the record has been fully committed

* test: fix tests

---------

Co-authored-by: Vincent Molinié <[email protected]>

Author: VincentMolinie

addon/record-data.js

@@ -671,10 +671,7 @@ export default class FragmentRecordData extends RecordData {
       this._fragmentsOrInFlight
     )) {
       const behavior = this._fragmentBehavior[key];
-      const oldFragment =
-        key in this._inFlightFragments
-          ? this._inFlightFragments[key]
-          : this._fragmentData[key];
+      const oldFragment = this._fragmentData[key];
       diffData[key] = [
         behavior.canonicalState(oldFragment),
         behavior.currentState(newFragment),

tests/unit/fragment_test.js

@@ -201,6 +201,59 @@ module('unit - `MF.Fragment`', function (hooks) {
     );
   });
 
+  test("fragment properties that are initially null are indicated in the owner record's `changedAttributes`", async function (assert) {
+    store.push({
+      data: {
+        type: 'person',
+        id: 1,
+        attributes: {
+          name: null,
+        },
+      },
+    });
+
+    const person = await store.findRecord('person', 1);
+    person.set('name', {
+      first: 'Rob',
+      last: 'Stark',
+    });
+
+    const [oldName, newName] = person.changedAttributes().name;
+    assert.deepEqual(
+      oldName,
+      null,
+      'old fragment is indicated in the diff object'
+    );
+    assert.deepEqual(
+      newName,
+      { first: 'Rob', last: 'Stark', prefixes: [] },
+      'new fragment is indicated in the diff object'
+    );
+
+    person._internalModel.adapterWillCommit();
+
+    const [oldNameAfterWillCommit, newNameAfterWillCommit] =
+      person.changedAttributes().name;
+    assert.deepEqual(
+      oldNameAfterWillCommit,
+      null,
+      'old fragment is indicated in the diff object'
+    );
+    assert.deepEqual(
+      newNameAfterWillCommit,
+      { first: 'Rob', last: 'Stark', prefixes: [] },
+      'new fragment is indicated in the diff object'
+    );
+
+    person._internalModel.adapterDidCommit();
+
+    assert.strictEqual(
+      person.changedAttributes().name,
+      undefined,
+      'changedAttributes is reset after commit'
+    );
+  });
+
   test('changes to attributes can be rolled back', async function (assert) {
     store.push({
       data: {