Add warnings in doc

.github/workflows/ci.yaml

@@ -79,7 +79,7 @@ jobs:
           python -m pytest -v --ignore=tests/benchmarks -m "jstest" tests
 
   tests-no-mpl:
-    name: Docs no matplotlib
+    name: Test matplotlib uninstalled
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4

noxfile.py

@@ -27,8 +27,7 @@ def tests_no_mpl(session):
     session.run("pip", "uninstall", "-y", "matplotlib", "numpy", silent=True)
     session.run("echo", "TEST FINAL PACKAGE LIST")
     session.run("pip", "freeze")
-    posargs = session.posargs or ["tests/no_mpl_tests.py"]
-    session.run("pytest", *posargs, external=True)
+    session.run("pytest", "tests/no_mpl_tests.py", *session.posargs, external=True)
 
 
 @session(python="3.10")

sphinx_needs/directives/needbar.py

@@ -184,13 +184,20 @@ def process_needbar(app: Sphinx, doctree: nodes.document, fromdocname: str, foun
     # NEEDFLOW
     # for node in doctree.findall(Needbar):
     for node in found_nodes:
-        if matplotlib is None or not needs_config.include_needs:
+        if not needs_config.include_needs:
             remove_node_from_tree(node)
             continue
 
         id = node.attributes["ids"][0]
         current_needbar = needs_data.get_or_create_bars()[id]
 
+        if matplotlib is None:
+            message = "Matplotlib missing for needbar plot"
+            if current_needbar["title"]:
+                message += f" {current_needbar['title']!r}"
+            node.replace_self(nodes.error("", nodes.paragraph(text=message)))
+            continue
+
         # 1. define constants
         error_id = current_needbar["error_id"]
 

sphinx_needs/directives/needpie.py

@@ -120,13 +120,20 @@ def process_needpie(app: Sphinx, doctree: nodes.document, fromdocname: str, foun
     # NEEDFLOW
     # for node in doctree.findall(Needpie):
     for node in found_nodes:
-        if matplotlib is None or not needs_config.include_needs:
+        if not needs_config.include_needs:
             remove_node_from_tree(node)
             continue
 
         id = node.attributes["ids"][0]
         current_needpie = needs_data.get_or_create_pies()[id]
 
+        if matplotlib is None:
+            message = "Matplotlib missing for needpie plot"
+            if current_needpie["title"]:
+                message += f" {current_needpie['title']!r}"
+            node.replace_self(nodes.error("", nodes.paragraph(text=message)))
+            continue
+
         # Set matplotlib style
         style_previous_to_script_execution = matplotlib.rcParams
         if current_needpie["style"]: