test: cover CSV export helper

tests/test_export.py

@@ -0,0 +1,49 @@
+import io
+import sqlite3
+
+import pytest
+
+from sqlite_utils.export import rows_to_csv_file
+
+
+def _cursor():
+    db = sqlite3.connect(":memory:")
+    db.execute("create table creatures (id integer, name text)")
+    db.executemany(
+        "insert into creatures (id, name) values (?, ?)",
+        ((1, "Cleo"), (2, "Cardi, Jr.")),
+    )
+    return db, db.execute("select id, name from creatures order by id")
+
+
+def test_rows_to_csv_file():
+    db, cursor = _cursor()
+    output = io.StringIO(newline="")
+    rows_to_csv_file(cursor, output, lineterminator="\n")
+    assert output.getvalue() == 'id,name\n1,Cleo\n2,"Cardi, Jr."\n'
+    db.close()
+
+
+def test_rows_to_csv_file_without_header():
+    db, cursor = _cursor()
+    output = io.StringIO(newline="")
+    rows_to_csv_file(cursor, output, header=False, lineterminator="\n")
+    assert output.getvalue() == '1,Cleo\n2,"Cardi, Jr."\n'
+    db.close()
+
+
+def test_rows_to_csv_file_tsv():
+    db, cursor = _cursor()
+    output = io.StringIO(newline="")
+    rows_to_csv_file(cursor, output, dialect="excel-tab", lineterminator="\n")
+    assert output.getvalue() == "id\tname\n1\tCleo\n2\tCardi, Jr.\n"
+    db.close()
+
+
+def test_rows_to_csv_file_requires_result_columns_for_header():
+    db = sqlite3.connect(":memory:")
+    cursor = db.execute("create table creatures (id integer)")
+    output = io.StringIO(newline="")
+    with pytest.raises(ValueError, match="Cursor does not have result columns"):
+        rows_to_csv_file(cursor, output)
+    db.close()