Fix requires_geos with methods (#376)

.readthedocs.yml

@@ -8,6 +8,7 @@ version: 2
 # Build documentation in the docs/ directory with Sphinx
 sphinx:
   configuration: docs/conf.py
+  fail_on_warning: true
 
 # Build documentation with MkDocs
 #mkdocs:

pygeos/decorators.py

@@ -37,9 +37,19 @@ def wrapped(*args, **kwargs):
             def wrapped(*args, **kwargs):
                 raise UnsupportedGEOSOperation(msg)
 
-        if wrapped.__doc__:
-            wrapped.__doc__ = wrapped.__doc__.replace(
-                "\n\n", "\n\n    .. note:: {}\n\n".format(msg), 1
+        doc = wrapped.__doc__
+        if doc:
+            # Insert the message at the first double newline
+            position = doc.find("\n\n") + 2
+            # Figure out the indentation level
+            indent = 2
+            while True:
+                if doc[position + indent] == " ":
+                    indent += 1
+                else:
+                    break
+            wrapped.__doc__ = doc.replace(
+                "\n\n", "\n\n{}.. note:: {}\n\n".format(" " * indent, msg), 1
             )
 
         return wrapped

pygeos/tests/test_misc.py

@@ -68,13 +68,22 @@ def func():
     """
 
 
+class SomeClass:
+    def func(self):
+        """Docstring that will be mocked.
+        A multiline.
+
+        Some description.
+        """
+
+
 expected_docstring = """Docstring that will be mocked.
-    A multiline.
+{indent}A multiline.
 
-    .. note:: 'func' requires at least GEOS {}.
+{indent}.. note:: 'func' requires at least GEOS {version}.
 
-    Some description.
-    """
+{indent}Some description.
+{indent}"""
 
 
 @pytest.mark.parametrize("version", ["3.7.0", "3.7.1", "3.6.2"])
@@ -89,15 +98,23 @@ def test_requires_geos_not_ok(version, mocked_geos_version):
     with pytest.raises(pygeos.UnsupportedGEOSOperation):
         wrapped()
 
-    assert wrapped.__doc__ == expected_docstring.format(version)
+    assert wrapped.__doc__ == expected_docstring.format(version=version, indent=" " * 4)
 
 
 @pytest.mark.parametrize("version", ["3.6.0", "3.8.0"])
 def test_requires_geos_doc_build(version, mocked_geos_version, sphinx_doc_build):
     """The requires_geos decorator always adapts the docstring."""
     wrapped = requires_geos(version)(func)
 
-    assert wrapped.__doc__ == expected_docstring.format(version)
+    assert wrapped.__doc__ == expected_docstring.format(version=version, indent=" " * 4)
+
+
+@pytest.mark.parametrize("version", ["3.6.0", "3.8.0"])
+def test_requires_geos_method(version, mocked_geos_version, sphinx_doc_build):
+    """The requires_geos decorator adjusts methods docstrings correctly"""
+    wrapped = requires_geos(version)(SomeClass.func)
+
+    assert wrapped.__doc__ == expected_docstring.format(version=version, indent=" " * 8)
 
 
 @multithreading_enabled