Add router add_subroute method

tests/test_router.py

@@ -79,3 +79,32 @@ def test_router_pattern_match():
 
     with pytest.raises(NotFoundException, match='404\tNot Found: asd'):
         r.match('GET', 'asd/basdf')
+
+
+def test_subroutes():
+    async def f(*args):
+        pass
+
+    async def d(*args):
+        pass
+
+    r1 = Router()
+    r2 = Router()
+
+    r1.add('GET', '/asdf', f)
+    r2.add('GET', '/asdf/a', d)
+    r1.add_subroute('', r2)
+
+    assert r1.match('GET', '/asdf') == ({}, f)
+    assert r1.match('GET', '/asdf/a') == ({}, d)
+    r1.add_subroute('/asdf', r2)
+    assert r1.match('GET', '/asdf/asdf/a') == ({}, d)
+
+    r1.add_subroute('/asdf' * 5, r2)
+    assert r1.match('GET', '/asdf' * 5 + '/asdf/a') == ({}, d)
+
+    with pytest.raises(NotFoundException):
+        r1.match('GET', '/asdf/' * 5 + '/asdf/a')
+
+    r1.add_subroute('/asdf/' * 5, r2)
+    assert r1.match('GET', '/asdf/' * 5 + '/asdf/a') == ({}, d)