From 593bcef515bf9e40a9a6c21d9327f497697d6969 Mon Sep 17 00:00:00 2001
From: Marc Wouts <marc.wouts@gmail.com>
Date: Sun, 7 Mar 2021 20:27:24 +0100
Subject: [PATCH] Use non-random cell ids in tests (#751)

* Use non-random cell ids in tests

* Update CHANGELOG.md
---
 docs/CHANGELOG.md     |  3 ++-
 tests/conftest.py     | 15 +++++++++++++++
 tests/test_cell_id.py | 10 ++++++++++
 3 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_cell_id.py

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 6b5745896..91efed852 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -5,7 +5,8 @@ Jupytext ChangeLog
 -------------------
 
 **Fixed**
-- We have updated `marked`, an indirect dependency of the `jupyterlab-jupytext` extension, to fix a moderate vulnerability (#750).
+- We have updated `marked`, an indirect dependency of the `jupyterlab-jupytext` extension, to fix a moderate vulnerability ([#750](https://github.com/mwouts/jupytext/issues/750)).
+- We use non-random cell ids in the tests to avoid test failures due to duplicate cell ids ([#747](https://github.com/mwouts/jupytext/issues/747))
 
 
 1.10.2 (2021-02-17)
diff --git a/tests/conftest.py b/tests/conftest.py
index f9a36d895..d35315e15 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -3,6 +3,7 @@
 
 import pytest
 from git import Repo
+from nbformat.v4 import nbbase
 from nbformat.v4.nbbase import (
     new_code_cell,
     new_markdown_cell,
@@ -90,3 +91,17 @@ def notebook_with_outputs():
             }
         },
     )
+
+
+"""To make sure that cell ids are distinct we use a global counter.
+    This solves https://github.com/mwouts/jupytext/issues/747"""
+global_cell_count = 0
+
+
+def generate_corpus_id():
+    global global_cell_count
+    global_cell_count += 1
+    return f"cell-{global_cell_count}"
+
+
+nbbase.random_cell_id = generate_corpus_id
diff --git a/tests/test_cell_id.py b/tests/test_cell_id.py
new file mode 100644
index 000000000..4d65e3a83
--- /dev/null
+++ b/tests/test_cell_id.py
@@ -0,0 +1,10 @@
+from nbformat.v4.nbbase import new_code_cell
+
+
+def test_cell_id_is_not_random():
+    id1 = new_code_cell().id
+    id2 = new_code_cell().id
+
+    n1 = int(id1.split("-")[1])
+    n2 = int(id2.split("-")[1])
+    assert n2 == n1 + 1