--no-skip-false option, plus docs - closes #527

tests/test_cli_convert.py

@@ -626,3 +626,30 @@ def test_convert_initialization_pattern(fresh_db_and_path):
     assert list(db["names"].rows) == [
         {"id": 1, "name": "17"},
     ]
+
+
+@pytest.mark.parametrize(
+    "no_skip_false,expected",
+    (
+        (True, 1),
+        (False, 0),
+    ),
+)
+def test_convert_no_skip_false(fresh_db_and_path, no_skip_false, expected):
+    db, db_path = fresh_db_and_path
+    args = [
+        "convert",
+        db_path,
+        "t",
+        "x",
+        "-",
+    ]
+    if no_skip_false:
+        args.append("--no-skip-false")
+    db["t"].insert_all([{"x": 0}, {"x": 1}])
+    assert db["t"].get(1)["x"] == 0
+    assert db["t"].get(2)["x"] == 1
+    result = CliRunner().invoke(cli.cli, args, input="value + 1")
+    assert 0 == result.exit_code, result.output
+    assert db["t"].get(1)["x"] == expected
+    assert db["t"].get(2)["x"] == 2