Add integration test for IPv6 address in URL for SQL DBs (#4077)

Add an integration test for connecting to SQL databases with an IPv6
address in a connection string.

This serves as a regression test for the fix for PostgreSQL and MySQL in
1548dc1, as well as confirms that this
already works on MS SQL.

Ref: #4051
Ref: prisma/prisma#18079

schema-engine/sql-migration-tests/tests/initialization/mod.rs

@@ -84,3 +84,28 @@ fn connecting_to_a_postgres_database_with_missing_schema_creates_it(api: TestApi
         assert!(schema_exists)
     }
 }
+
+#[test_connector(exclude(Sqlite))]
+fn ipv6_addresses_are_supported_in_connection_strings(api: TestApi) {
+    let url = api.connection_string().replace("localhost", "[::1]");
+    assert!(url.contains("[::1]"));
+
+    let provider = api.provider();
+
+    let schema = format!(
+        r#"
+        datasource db {{
+            provider = "{provider}"
+            url = "{url}"
+        }}
+        "#
+    );
+
+    let engine = schema_api(Some(schema.clone()), None).unwrap();
+    tok(
+        engine.ensure_connection_validity(schema_core::json_rpc::types::EnsureConnectionValidityParams {
+            datasource: schema_core::json_rpc::types::DatasourceParam::SchemaString(SchemaContainer { schema }),
+        }),
+    )
+    .unwrap();
+}