fix: don't call overloaded versions of find functions internally

lib/model.js

@@ -1999,7 +1999,7 @@ class Model {
     }
 
     // Bypass a possible overloaded findOne
-    return await this.findOne(options);
+    return await Model.findOne.call(this, options);
   }
 
   /**
@@ -2034,9 +2034,9 @@ class Model {
     }
 
     // Bypass a possible overloaded findAll.
-    return await this.findAll(_.defaults(options, {
+    return await Model.findAll.call(this, (_.defaults(options, {
       plain: true,
-    }));
+    })));
   }
 
   /**

test/unit/model/find-by-pk.test.js

@@ -0,0 +1,42 @@
+'use strict';
+
+const chai = require('chai');
+
+const expect = chai.expect;
+const Support = require('../support');
+
+const Sequelize = Support.Sequelize;
+const Op = Sequelize.Op;
+const current = Support.sequelize;
+const sinon = require('sinon');
+const DataTypes = require('../../../lib/data-types');
+
+describe(Support.getTestDialectTeaser('Model'), () => {
+  describe('method findByPk', () => {
+    beforeEach(function () {
+      this.stub = sinon.stub(Sequelize.Model, 'findAll').resolves();
+    });
+    afterEach(() => {
+      sinon.restore();
+    });
+
+    it('should call internal findOne() method if findOne() is overridden', async () => {
+      const Model = current.define('model', {
+        unique1: {
+          type: DataTypes.INTEGER,
+          unique: 'unique',
+        },
+        unique2: {
+          type: DataTypes.INTEGER,
+          unique: 'unique',
+        },
+      });
+      Model.findOne = sinon.stub();
+      sinon.spy(Sequelize.Model, 'findOne');
+
+      await Model.findByPk(1);
+      Model.findOne.should.not.have.been.called;
+      Sequelize.Model.findOne.should.have.been.called;
+    });
+  });
+});

test/unit/model/findone.test.js → test/unit/model/find-one.test.js

@@ -107,5 +107,22 @@ describe(Support.getTestDialectTeaser('Model'), () => {
       await Model.findOne({ where: { unique1: 42 } });
       expect(this.stub.getCall(0).args[0]).to.be.an('object').to.have.property('limit');
     });
+    it('should call internal findAll() method if findOne() is overridden', async () => {
+      const Model = current.define('model', {
+        unique1: {
+          type: DataTypes.INTEGER,
+          unique: 'unique',
+        },
+        unique2: {
+          type: DataTypes.INTEGER,
+          unique: 'unique',
+        },
+      });
+      Model.findAll = sinon.stub();
+
+      await Model.findOne();
+      Model.findAll.should.not.have.been.called;
+      Sequelize.Model.findAll.should.have.been.called;
+    });
   });
 });