improve coverage

tests/node_tests/helpers.py

@@ -63,3 +63,129 @@ def test_list_channels():
         folder_node = Folder()
         folder_result = folder_node.list_files(tmpdir)
         assert folder_result == tuple(entry["path"] for entry in paths)
+
+
+def test_measurement_helpers():
+    from backend.nodes.helpers import _measurement_names, _measurement_entry, _measurement_value
+    from backend.data_types import RecordTable
+
+    table = RecordTable([
+        {"quantity": "Rq", "value": 0.5, "unit": "nm"},
+        {"quantity": "Ra", "value": 0.3, "unit": "nm"},
+        {"quantity": "Rq", "value": 0.5, "unit": "nm"},  # duplicate — deduplicated in names
+    ])
+
+    names = _measurement_names(table)
+    assert names == ["Rq", "Ra"]
+
+    row = _measurement_entry(table, "Ra")
+    assert row["value"] == 0.3
+
+    # falls back to first when selection not found
+    row_fallback = _measurement_entry(table, "nonexistent")
+    assert row_fallback["quantity"] == "Rq"
+
+    val = _measurement_value(table, "Ra")
+    assert val == 0.3
+
+
+def test_measurement_value_errors():
+    from backend.nodes.helpers import _measurement_value
+    from backend.data_types import RecordTable
+
+    empty = RecordTable([])
+    try:
+        _measurement_value(empty, "anything")
+        assert False, "should raise"
+    except ValueError:
+        pass
+
+    bool_table = RecordTable([{"quantity": "flag", "value": True}])
+    try:
+        _measurement_value(bool_table, "flag")
+        assert False, "should raise"
+    except ValueError:
+        pass
+
+
+def test_format_with_unit():
+    from backend.nodes.helpers import _format_with_unit, _format_numeric
+
+    assert _format_numeric(0.0) == "0"
+    assert not np.isfinite(float('inf')) or _format_numeric(float('inf')) is not None
+
+    # plain number no unit
+    result = _format_with_unit(1.5, "")
+    assert "1.5" in result
+
+    # prefixable unit gets SI prefix
+    result_nm = _format_with_unit(1e-9, "m")
+    assert "n" in result_nm or "1e" in result_nm
+
+    # non-prefixable unit is left as-is
+    result_bare = _format_with_unit(3.14, "rad")
+    assert "3.14" in result_bare and "rad" in result_bare
+
+    # zero value
+    result_zero = _format_with_unit(0.0, "m")
+    assert "0" in result_zero
+
+
+def test_table_and_array_ops():
+    from backend.nodes.helpers import (
+        TABLE_OPS, ARRAY_OPS, extract_numeric_table_values,
+        resolve_table_column_name, _common_table_unit,
+    )
+    from backend.data_types import RecordTable
+
+    values = np.array([1.0, 2.0, 3.0, 4.0, 5.0])
+    assert TABLE_OPS["min"](values) == 1.0
+    assert TABLE_OPS["max"](values) == 5.0
+    assert TABLE_OPS["mean"](values) == 3.0
+    assert TABLE_OPS["sum"](values) == 15.0
+    assert TABLE_OPS["range"](values) == 4.0
+    assert TABLE_OPS["count"](values) == 5.0
+    assert TABLE_OPS["median"](values) == 3.0
+    assert TABLE_OPS["std"](values) > 0
+    assert TABLE_OPS["variance"](values) > 0
+
+    assert ARRAY_OPS["rms"](values) > 0
+    assert ARRAY_OPS["std"](values) > 0
+
+    table = RecordTable([
+        {"quantity": "A", "value": 1.0, "unit": "m"},
+        {"quantity": "B", "value": 2.0, "unit": "m"},
+        {"not_a_dict": True},
+        {"quantity": "C", "value": "not_a_number"},
+    ])
+    nums = extract_numeric_table_values(table, "value")
+    assert nums == [1.0, 2.0]
+
+    col = resolve_table_column_name(table, "")
+    assert col == "value"
+
+    unit = _common_table_unit(table, "value")
+    assert unit == "m"
+
+
+def test_square_unit_and_apply():
+    from backend.nodes.helpers import _square_unit, _apply_scalar_unit
+
+    assert _square_unit("m") == "m^2"
+    assert _square_unit("m/s") == "(m/s)^2"
+    assert _square_unit("") == ""
+
+    assert _apply_scalar_unit("m", "variance") == "m^2"
+    assert _apply_scalar_unit("m", "count") == "count"
+    assert _apply_scalar_unit("m", "mean") == "m"
+    assert _apply_scalar_unit("", "mean") == ""
+
+
+def test_nice_length():
+    from backend.nodes.helpers import _nice_length
+
+    assert _nice_length(0.0) == 0.0
+    assert _nice_length(float('inf')) == 0.0
+    assert _nice_length(7.3) == 5.0
+    assert _nice_length(1500.0) == 1000.0
+    assert _nice_length(0.003) == 0.002