show some navigation on every page

closes #1

tests/instance/pages/subdir-with-title/index.md

@@ -0,0 +1,3 @@
+Title:  SUB!
+
+# subdir-with-title

tests/instance/pages/subdir-with-title/page.md

@@ -0,0 +1 @@
+test page

tests/instance/pages/subdir/index.md

@@ -0,0 +1 @@
+# another page

tests/instance/pages/subdir/page.md

@@ -0,0 +1,3 @@
+Title:  Page
+
+# hello

tests/test_pages.py

@@ -1,7 +1,7 @@
 """Test page views and helper methods."""
 import re
 
-from incorporealcms.pages import resolve_page_file
+from incorporealcms.pages import generate_parent_navs, resolve_page_file
 
 
 def test_resolve_page_file_dir_to_index():
@@ -44,3 +44,24 @@ def test_page_has_modified_timestamp(client):
     response = client.get('/')
     assert response.status_code == 200
     assert re.search(r'Last modified: ....-..-.. ..:..:.. ...', response.data.decode()) is not None
+
+
+def test_generate_page_navs_index(app):
+    with app.app_context():
+        assert generate_parent_navs('pages/index.md') == [('incorporeal.org', '/')]
+
+
+def test_generate_page_navs_subdir_index(app):
+    with app.app_context():
+        assert generate_parent_navs('pages/subdir/index.md') == [('incorporeal.org', '/')]
+
+
+def test_generate_page_navs_subdir_real_page(app):
+    with app.app_context():
+        assert generate_parent_navs('pages/subdir/page.md') == [('incorporeal.org', '/'), ('subdir', '/subdir/')]
+
+
+def test_generate_page_navs_subdir_with_title_parsing_real_page(app):
+    with app.app_context():
+        assert generate_parent_navs('pages/subdir-with-title/page.md') == [('incorporeal.org', '/'),
+                                                                           ('SUB!', '/subdir-with-title/')]