chore: fix flaky system tests (#84)

* Remove a mutation that could affect subsequent tests.
* Make error message from API more flexible.

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Fixes #<issue_number_goes_here> 🦕

Author: tswast

tests/system/small/test_pandas_options.py

@@ -75,7 +75,7 @@ def test_read_gbq_start_sets_session_location(
     # Now read_gbq* from another location should fail
     with pytest.raises(
         google.api_core.exceptions.NotFound,
-        match=f"404 Not found: Dataset {dataset_id_permanent} was not found in location {tokyo_location}",
+        match=dataset_id_permanent,
     ):
         read_method(query)
 
@@ -100,7 +100,7 @@ def test_read_gbq_start_sets_session_location(
     # Now read_gbq* from another location should fail
     with pytest.raises(
         google.api_core.exceptions.NotFound,
-        match=f"404 Not found: Dataset {dataset_id_permanent_tokyo} was not found in location US",
+        match=dataset_id_permanent_tokyo,
     ):
         read_method(query_tokyo)
 
@@ -146,7 +146,7 @@ def test_read_gbq_after_session_start_must_comply_with_default_location(
     # Doing read_gbq* from a table in another location should fail
     with pytest.raises(
         google.api_core.exceptions.NotFound,
-        match=f"404 Not found: Dataset {dataset_id_permanent_tokyo} was not found in location US",
+        match=dataset_id_permanent_tokyo,
     ):
         read_method(query_tokyo)
 
@@ -194,7 +194,7 @@ def test_read_gbq_must_comply_with_set_location_US(
     # Starting user journey with read_gbq* from another location should fail
     with pytest.raises(
         google.api_core.exceptions.NotFound,
-        match=f"404 Not found: Dataset {dataset_id_permanent_tokyo} was not found in location US",
+        match=dataset_id_permanent_tokyo,
     ):
         read_method(query_tokyo)
 
@@ -244,7 +244,7 @@ def test_read_gbq_must_comply_with_set_location_non_US(
     # Starting user journey with read_gbq* from another location should fail
     with pytest.raises(
         google.api_core.exceptions.NotFound,
-        match=f"404 Not found: Dataset {dataset_id_permanent} was not found in location {tokyo_location}",
+        match=dataset_id_permanent,
     ):
         read_method(query)
 

tests/system/small/test_session.py

@@ -321,11 +321,10 @@ def test_read_pandas_multi_index(session, scalars_pandas_df_multi_index):
 
 
 def test_read_pandas_rowid_exists_adds_suffix(session, scalars_pandas_df_default_index):
-    scalars_pandas_df_default_index["rowid"] = np.arange(
-        scalars_pandas_df_default_index.shape[0]
-    )
+    pandas_df = scalars_pandas_df_default_index.copy()
+    pandas_df["rowid"] = np.arange(pandas_df.shape[0])
 
-    df = session.read_pandas(scalars_pandas_df_default_index)
+    df = session.read_pandas(pandas_df)
     total_order_col = df._block._expr._ordering.total_order_col
     assert total_order_col and total_order_col.column_id == "rowid_2"