hdr: add _Footer._prior_headerfooter

scanny · scanny · commit c77cae043b7d · 2019-01-06T14:26:12.000-08:00
diff --git a/docx/section.py b/docx/section.py
@@ -315,6 +315,15 @@ def _has_definition(self):
         footerReference = self._sectPr.get_footerReference(WD_HEADER_FOOTER.PRIMARY)
         return False if footerReference is None else True
 
+    @property
+    def _prior_headerfooter(self):
+        """|_Footer| proxy on prior sectPr element or None if this is first section."""
+        preceding_sectPr = self._sectPr.preceding_sectPr
+        return (
+            None if preceding_sectPr is None
+            else _Footer(preceding_sectPr, self._document_part)
+        )
+
 
 class _Header(_BaseHeaderFooter):
     """Page header."""
diff --git a/tests/test_section.py b/tests/test_section.py
@@ -531,6 +531,29 @@ def it_knows_when_it_has_a_definition_to_help(self, has_definition_fixture):
 
         assert has_definition is expected_value
 
+    def it_provides_access_to_the_prior_Footer_to_help(
+        self, request, document_part_, footer_
+    ):
+        doc_elm = element("w:document/(w:sectPr,w:sectPr)")
+        prior_sectPr, sectPr = doc_elm[0], doc_elm[1]
+        footer = _Footer(sectPr, document_part_)
+        # ---mock must occur after construction of "real" footer---
+        _Footer_ = class_mock(request, "docx.section._Footer", return_value=footer_)
+
+        prior_footer = footer._prior_headerfooter
+
+        _Footer_.assert_called_once_with(prior_sectPr, document_part_)
+        assert prior_footer is footer_
+
+    def but_it_returns_None_when_its_the_first_footer(self):
+        doc_elm = element("w:document/w:sectPr")
+        sectPr = doc_elm[0]
+        footer = _Footer(sectPr, None)
+
+        prior_footer = footer._prior_headerfooter
+
+        assert prior_footer is None
+
     # fixtures -------------------------------------------------------
 
     @pytest.fixture(
@@ -549,6 +572,10 @@ def has_definition_fixture(self, request):
     def document_part_(self, request):
         return instance_mock(request, DocumentPart)
 
+    @pytest.fixture
+    def footer_(self, request):
+        return instance_mock(request, _Footer)
+
     @pytest.fixture
     def footer_part_(self, request):
         return instance_mock(request, FooterPart)
