test(rust): cover named memory databases on Windows (#3839)

## Summary\n\n- add a create-table regression for a named database\n-
assert that the derived table URI uses URL separators\n- restore the
four query tests that were moved to temporary files for #1051\n\n## Root
cause\n\n historically joined table names with . On Windows this
inserted a backslash into , so Lance interpreted the URI as an invalid
local filename. The production URI builder now preserves forward slashes
for URI schemes; this change restores the issue-specific tests and adds
direct regression coverage for table creation and the derived URI.\n\n##
Validation\n\n- \n- \n- (passes with four pre-existing warnings in
unrelated remote-table code)\n-
running 814 tests

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test result: ok. 813 passed; 0 failed; 1 ignored; 0 measured; 0 filtered
out; finished in 7.76s


running 39 tests
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test result: ok. 39 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.23s


running 6 tests
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test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.03s


running 5 tests
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test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.10s


running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.00s


running 2 tests
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test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.00s


running 2 tests
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test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered
out; finished in 0.00s (867 passed, 1 ignored)\n- focused named-memory
create and restored query tests\n\nFixes #1051\n\n<!--
lance-gatekeeper-fix:v1 agent=5ddf7a9520292b4cbaa58b9ea5a1fe76
generation=1 -->

Co-authored-by: Gatefixer <313497061+lancedb-gatefixer[bot]@users.noreply.github.com>

rust/lancedb/src/connection/create_table.rs

@@ -202,6 +202,17 @@ mod tests {
         assert_eq!(table.count_rows(None).await.unwrap(), 0);
     }
 
+    #[tokio::test]
+    async fn create_table_in_named_memory_database() {
+        let db = connect("memory://foo").execute().await.unwrap();
+        let batch = record_batch!(("id", Int64, [1, 2, 3])).unwrap();
+
+        let table = db.create_table("my_table", batch).execute().await.unwrap();
+
+        assert_eq!(table.uri().await.unwrap(), "memory://foo/my_table.lance");
+        assert_eq!(table.count_rows(None).await.unwrap(), 3);
+    }
+
     async fn test_create_table_with_data<T>(data: T)
     where
         T: Scannable + 'static,

rust/lancedb/src/query.rs

@@ -1661,14 +1661,8 @@ mod tests {
 
     #[tokio::test]
     async fn test_setters_getters() {
-        // TODO: Switch back to memory://foo after https://github.com/lancedb/lancedb/issues/1051
-        // is fixed
-        let tmp_dir = tempdir().unwrap();
-        let dataset_path = tmp_dir.path().join("test.lance");
-        let uri = dataset_path.to_str().unwrap();
-
         let batches = make_test_batches();
-        let conn = connect(uri).execute().await.unwrap();
+        let conn = connect("memory://foo").execute().await.unwrap();
         let table = conn
             .create_table("my_table", batches)
             .execute()
@@ -1763,14 +1757,8 @@ mod tests {
 
     #[tokio::test]
     async fn test_execute() {
-        // TODO: Switch back to memory://foo after https://github.com/lancedb/lancedb/issues/1051
-        // is fixed
-        let tmp_dir = tempdir().unwrap();
-        let dataset_path = tmp_dir.path().join("test.lance");
-        let uri = dataset_path.to_str().unwrap();
-
         let batches = make_non_empty_batches();
-        let conn = connect(uri).execute().await.unwrap();
+        let conn = connect("memory://foo").execute().await.unwrap();
         let table = conn
             .create_table("my_table", batches)
             .execute()
@@ -1889,14 +1877,8 @@ mod tests {
 
     #[tokio::test]
     async fn test_select_with_transform() {
-        // TODO: Switch back to memory://foo after https://github.com/lancedb/lancedb/issues/1051
-        // is fixed
-        let tmp_dir = tempdir().unwrap();
-        let dataset_path = tmp_dir.path().join("test.lance");
-        let uri = dataset_path.to_str().unwrap();
-
         let batches = make_non_empty_batches();
-        let conn = connect(uri).execute().await.unwrap();
+        let conn = connect("memory://foo").execute().await.unwrap();
         let table = conn
             .create_table("my_table", batches)
             .execute()
@@ -1993,15 +1975,9 @@ mod tests {
 
     #[tokio::test]
     async fn test_execute_no_vector() {
-        // TODO: Switch back to memory://foo after https://github.com/lancedb/lancedb/issues/1051
-        // is fixed
-        let tmp_dir = tempdir().unwrap();
-        let dataset_path = tmp_dir.path().join("test.lance");
-        let uri = dataset_path.to_str().unwrap();
-
         // test that it's ok to not specify a query vector (just filter / limit)
         let batches = make_non_empty_batches();
-        let conn = connect(uri).execute().await.unwrap();
+        let conn = connect("memory://foo").execute().await.unwrap();
         let table = conn
             .create_table("my_table", batches)
             .execute()