fix: fix up some code, handle new errors etc

Author: ollz272

python/pydantic_core/_pydantic_core.pyi

@@ -225,6 +225,7 @@ class MultiHostUrl(SupportsAllComparisons):
         user: Optional[str] = None,
         password: Optional[str] = None,
         host: str,
+        hosts: Optional[dict] = None,
         port: Optional[str] = None,
         path: Optional[str] = None,
         query: Optional[str] = None,

src/url.rs

@@ -373,25 +373,30 @@ impl PyMultiHostUrl {
         password: Option<&str>,
         port: Option<&str>,
     ) -> PyResult<&'a PyAny> {
-        let mut url = if hosts.is_some() {
+        let mut url = if hosts.is_some() && host.is_some() {
+            return Err(PyValueError::new_err("Only one of `host` or `hosts` may be set"));
+        }
+        else if hosts.is_some() {
             // check all of host / user / password / port empty
             // build multi-host url
             todo!()
-        } else if let Some(host) = host {
+        }
+        else if let Some(host) = host {
             let user_password = match (user, password) {
                 (Some(user), None) => format!("{user}@"),
                 (None, Some(password)) => format!(":{password}@"),
                 (Some(user), Some(password)) => format!("{user}:{password}@"),
                 (None, None) => String::new(),
             };
-            format!("{scheme}://{user_password}{host}")
+            let mut single_host_url = format!("{scheme}://{user_password}{host}");
+            if let Some(port) = port {
+                single_host_url.push(':');
+                single_host_url.push_str(port);
+            };
+            single_host_url
         } else {
             return Err(PyValueError::new_err("expected either `host` or `hosts` to be set"));
         };
-        if let Some(port) = port {
-            url.push(':');
-            url.push_str(port);
-        }
         if let Some(path) = path {
             url.push('/');
             url.push_str(path);

tests/validators/test_url.py

@@ -1233,6 +1233,46 @@ def test_multi_url_build() -> None:
     assert str(url) == 'postgresql://testuser:[email protected]:5432/database?sslmode=require#test'
 
 
+def test_multi_url_build_host_and_hosts_set() -> None:
+    hosts = [
+        {
+            'host': '127.0.0.1:5432',
+            'password': 'testpassword',
+            'username': 'testuser',
+            'port': '5432'
+        },
+        {
+            'host': '127.0.0.1:5432',
+            'password': 'testpassword',
+            'username': 'testuser',
+            'port': '5432'
+        },
+    ]
+    with pytest.raises(ValueError):
+        MultiHostUrl.build(
+            scheme='postgresql',
+            user='testuser',
+            password='testpassword',
+            host='127.0.0.1',
+            hosts=hosts,
+            port='5432',
+            path='database',
+            query='sslmode=require',
+            fragment='test',
+        )
+
+def test_multi_url_build_neither_host_and_hosts_set() -> None:
+    with pytest.raises(ValueError):
+        MultiHostUrl.build(
+            scheme='postgresql',
+            user='testuser',
+            password='testpassword',
+            port='5432',
+            path='database',
+            query='sslmode=require',
+            fragment='test',
+        )
+
 def test_url_build() -> None:
     url = Url.build(
         scheme='postgresql',