Quote the path in DataFrameReader.load when no format is given

duckdb/experimental/spark/sql/readwriter.py

@@ -116,7 +116,8 @@ def load(  # noqa: D102
             else:
                 raise ContributionsAcceptedError
         else:
-            rel = self.session.conn.sql(f"select * from {path}")
+            escaped_path = path.replace("'", "''")
+            rel = self.session.conn.sql(f"select * from '{escaped_path}'")
         df = DataFrame(rel, self.session)
         if schema:
             if not isinstance(schema, StructType):

tests/fast/spark/test_spark_read_load.py

@@ -0,0 +1,38 @@
+import pytest
+
+_ = pytest.importorskip("duckdb.experimental.spark")
+
+
+from spark_namespace import USE_ACTUAL_SPARK
+from spark_namespace.sql.types import Row
+
+
+@pytest.mark.skipif(
+    USE_ACTUAL_SPARK,
+    reason="load() without a format reads whatever the extension says here, while Spark defaults to parquet",
+)
+class TestSparkReadLoad:
+    def test_read_load_no_format(self, spark, tmp_path):
+        # 'load' without a 'format' falls back to building a bare SQL query out of the
+        # path, which must be quoted as a string literal or it cannot survive a path
+        # that contains anything the parser treats as syntax: a separator, a space, a colon.
+        sub_dir = tmp_path / "dir with space"
+        sub_dir.mkdir()
+        file_path = sub_dir / "basic.csv"
+        file_path.write_text("a,b\n1,2\n3,4\n")
+
+        df = spark.read.load(file_path.as_posix())
+        res = df.collect()
+
+        assert sorted(res) == sorted([Row(a=1, b=2), Row(a=3, b=4)])
+
+    def test_read_load_no_format_quote_in_path(self, spark, tmp_path):
+        sub_dir = tmp_path / "dir's"
+        sub_dir.mkdir()
+        file_path = sub_dir / "basic.csv"
+        file_path.write_text("a,b\n1,2\n")
+
+        df = spark.read.load(file_path.as_posix())
+        res = df.collect()
+
+        assert res == [Row(a=1, b=2)]