hdr: add Section.first_page_header

Author: scanny

docx/section.py

@@ -101,6 +101,15 @@ def first_page_footer(self):
         """
         return _Footer(self._sectPr, self._document_part, WD_HEADER_FOOTER.FIRST_PAGE)
 
+    @property
+    def first_page_header(self):
+        """|_Header| object defining header content for the first page of this section.
+
+        The content of this header definition is ignored unless the property
+        :attr:`.different_first_page_header_header` is set True.
+        """
+        return _Header(self._sectPr, self._document_part, WD_HEADER_FOOTER.FIRST_PAGE)
+
     @lazyproperty
     def footer(self):
         """|_Footer| object representing default page footer for this section.

features/sct-section.feature

@@ -42,7 +42,6 @@ Feature: Access and change section properties
      Then section.first_page_footer is a _Footer object
 
 
-  @wip
   Scenario: Section.first_page_header
     Given a Section object as section
      Then section.first_page_header is a _Header object

tests/test_section.py

@@ -154,6 +154,20 @@ def it_provides_access_to_its_first_page_footer(
         )
         assert footer is footer_
 
+    def it_provides_access_to_its_first_page_header(
+        self, document_part_, _Header_, header_
+    ):
+        sectPr = element("w:sectPr")
+        _Header_.return_value = header_
+        section = Section(sectPr, document_part_)
+
+        header = section.first_page_header
+
+        _Header_.assert_called_once_with(
+            sectPr, document_part_, WD_HEADER_FOOTER.FIRST_PAGE
+        )
+        assert header is header_
+
     def it_provides_access_to_its_default_footer(
         self, document_part_, _Footer_, footer_
     ):