Test on both marshmallow 3 and 4

Author: lafrech

.github/workflows/build-release.yml

@@ -12,8 +12,9 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - { name: '3.9', python: '3.9', tox: py39 }
-          - { name: '3.13', python: '3.13', tox: py313 }
+          - { name: '3.9-ma3', python: '3.9', tox: py39-marshmallow3 }
+          - { name: '3.9-ma4', python: '3.9', tox: py39-marshmallow4 }
+          - { name: '3.13-ma4', python: '3.13', tox: py313-marshmallow4 }
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5

pyproject.toml

@@ -26,7 +26,7 @@ requires-python = ">=3.9"
 dependencies = [
   "werkzeug>=3.0.1,<4",
   "flask>=3.0.2,<4",
-  "marshmallow>=3.24.1,<4",
+  "marshmallow>=3.24.1,<5",
   "webargs>=8.0.0,<9",
   "apispec[marshmallow]>=6.0.0,<7",
 ]
@@ -51,7 +51,7 @@ tests = [
   "coverage==7.8.0",
   "werkzeug==3.1.3",
   "flask==3.1.0",
-  "marshmallow==3.26.1",
+  "marshmallow",
   "webargs==8.6.0",
   "apispec==6.8.1",
   "PyYAML==6.0.2",

tox.ini

@@ -1,9 +1,15 @@
 [tox]
-envlist = lint,py39,py310,py311,py312,py313
+envlist =
+    lint
+    {py39,py310,py311,py312,py313}-marshmallow4
+    py39-marshmallow3
 skip_missing_interpreters = True
 
 [testenv]
 extras = tests
+deps =
+    marshmallow3: marshmallow>=3.26.1,<4
+    marshmallow4: marshmallow>=4.0.0,<5
 commands =
     pytest --cov=flask_smorest --cov-branch --cov-report=term-missing --cov-report=xml