feat: initial implementation

tests/test_negotiate.py

@@ -0,0 +1,48 @@
+"""Accept-header negotiation between WML and XHTML-MP."""
+from __future__ import annotations
+
+import pytest
+
+from smolweb.negotiate import FORMAT_HTML, FORMAT_WML, FORMAT_XHTML, negotiate
+
+
+class TestWildcardNeverSelectsWml:
+    def test_modern_browser_accept_header_gets_html(self):
+        # The exact header Firefox/Chrome send: a browser must never be
+        # handed WML through the */* wildcard.
+        accept = "text/html,application/xhtml+xml;q=0.9,image/webp,*/*;q=0.8"
+        assert negotiate(accept) == FORMAT_HTML
+
+    def test_bare_wildcard_gets_html(self):
+        assert negotiate("*/*") == FORMAT_HTML
+
+    def test_no_accept_header_gets_html(self):
+        assert negotiate(None) == FORMAT_HTML
+
+
+class TestLiteralMatches:
+    def test_wml_accept_header_gets_wml(self):
+        assert negotiate("text/vnd.wap.wml") == FORMAT_WML
+
+    def test_xhtml_mp_accept_header_gets_xhtml(self):
+        assert negotiate("application/vnd.wap.xhtml+xml") == FORMAT_XHTML
+
+    def test_wml_wins_when_both_present_with_higher_q(self):
+        accept = "text/vnd.wap.wml;q=1.0, application/vnd.wap.xhtml+xml;q=0.5"
+        assert negotiate(accept) == FORMAT_WML
+
+    def test_xhtml_wins_when_both_present_with_higher_q(self):
+        accept = "text/vnd.wap.wml;q=0.5, application/vnd.wap.xhtml+xml;q=1.0"
+        assert negotiate(accept) == FORMAT_XHTML
+
+    def test_unrelated_type_gets_html_fallback(self):
+        assert negotiate("application/json") == FORMAT_HTML
+
+
+class TestFormatOverride:
+    @pytest.mark.parametrize("fmt", [FORMAT_WML, FORMAT_XHTML, FORMAT_HTML])
+    def test_override_wins_regardless_of_accept(self, fmt):
+        assert negotiate("*/*", format_override=fmt) == fmt
+
+    def test_invalid_override_is_ignored(self):
+        assert negotiate("text/vnd.wap.wml", format_override="bogus") == FORMAT_WML