replace links that have .md suffixes with clean links

to aid viewing the raw markdown source in e.g. a gitlab source browser,
or to aid navigation in vim with "gf" style commands to jump between
files, allow the markdown source to specify foo.md or whatever/index.md
explicitly, yet generate the clean URLs for linking in the HTML output

this assumes that nginx is serving "foo" with foo.html, and "bar/" with
bar/index.html

Signed-off-by: Brian S. Stephan <bss@incorporeal.org>

tests/instance/pages/file-with-index.md-link.md

@@ -0,0 +1,6 @@
+[Cool](cool/index.md)
+[Anchored Cool](cool/index.md#anchor)
+[This Index](index.md)
+[Anchored This Index](index.md#anchor)
+[Parent](../index.md)
+[Anchored Parent](../index.md#anchor)

tests/instance/pages/file-with-md-link.md

@@ -0,0 +1,4 @@
+[Foo](foo.md)
+[Anchored Foo](foo.md#anchor)
+[Sub Foo](sub/foo.md)
+[Anchored Sub Foo](sub/foo.md#anchor)

tests/test_markdown.py

@@ -163,3 +163,23 @@ def test_parse_md_bad_file():
     """Test the direct results of parsing a markdown file."""
     with pytest.raises(ValueError):
         content, md, page_name, page_title, mtime = parse_md(os.path.join(PAGES_DIR, 'actually-a-png.md'), PAGES_DIR)
+
+
+def test_md_extension_in_source_link_is_stripped():
+    """Test that if a foo.md file link is specified in the Markdown, it is foo in the HTML."""
+    content, _, _, _, _ = parse_md(os.path.join(PAGES_DIR, 'file-with-md-link.md'), PAGES_DIR)
+    assert '<a href="foo">Foo</a>' in content
+    assert '<a href="foo#anchor">Anchored Foo</a>' in content
+    assert '<a href="sub/foo">Sub Foo</a>' in content
+    assert '<a href="sub/foo#anchor">Anchored Sub Foo</a>' in content
+
+
+def test_index_in_source_link_is_stripped():
+    """Test that if a index.md file link is specified in the Markdown, it is just the dir in the HTML."""
+    content, _, _, _, _ = parse_md(os.path.join(PAGES_DIR, 'file-with-index.md-link.md'), PAGES_DIR)
+    assert '<a href="cool/">Cool</a>' in content
+    assert '<a href="cool/#anchor">Anchored Cool</a>' in content
+    assert '<a href=".">This Index</a>' in content
+    assert '<a href=".#anchor">Anchored This Index</a>' in content
+    assert '<a href="../">Parent</a>' in content
+    assert '<a href="../#anchor">Anchored Parent</a>' in content