Added checklinks to tox and release.py

Following pytest-dev#1722 this will check all links in documentation.

Author: steffenschroeder

scripts/release.py

@@ -79,12 +79,19 @@ def fix_formatting():
     call(["pre-commit", "run", "--all-files"])
 
 
+def check_links():
+    """Runs sphinx-build -W -b linkcheck to check external links"""
+    print(f"{Fore.CYAN}[generate.check_links] {Fore.RESET}Checking links")
+    check_call(["tox", "-e", "docs-checklinks"])
+
+
 def pre_release(version):
     """Generates new docs, release announcements and creates a local tag."""
     announce(version)
     regen()
     changelog(version, write_out=True)
     fix_formatting()
+    check_links()
 
     msg = "Preparing release version {}".format(version)
     check_call(["git", "commit", "-a", "-m", msg])

tox.ini

@@ -15,6 +15,7 @@ envlist =
     doctesting
     py37-freeze
     docs
+    docs-checklinks
 
 [testenv]
 commands =
@@ -65,6 +66,14 @@ deps = -r{toxinidir}/doc/en/requirements.txt
 commands =
     sphinx-build -W -b html . _build
 
+[testenv:docs-checklinks]
+basepython = python3
+usedevelop = True
+changedir = doc/en
+deps = -r{toxinidir}/doc/en/requirements.txt
+commands =
+    sphinx-build -W -b linkcheck . _build
+
 [testenv:doctesting]
 basepython = python3
 skipsdist = True