[19.0][FIX] mis_builder: don't report unresolvable styles on intermediate passes

[MiquelRForgeFlow]

Description

KpiMatrix.set_values_detail_account is called on every pass of the computation loop, including the passes where a KPI is requeued because its expression referenced a KPI that was not evaluated yet. On those passes locals_dict is incomplete, so a style_expression referring to the KPI's own value fails and mis_safe_eval returns a DataError.

DataError subclasses Exception, so it is truthy and renders as an empty string. It was therefore passed to the style search and logged as Style '' not found. once per intermediate pass. That is noise on a perfectly correct report, and it hides the real problem when a style expression is actually broken:

    # a report whose KPI style expression references its own value, before
    ERROR ... kpimatrix: Style '' not found.
    ERROR ... kpimatrix: Style '' not found.
    ERROR ... kpimatrix: Style '' not found.

    # after
    (nothing)

    # a genuinely broken style expression, before
    ERROR ... kpimatrix: Style '' not found.

    # after
    ERROR ... kpimatrix: Error evaluating style expression
      <'Big' if unknown_kpi > 10 else 'Small'>: NameError: name 'unknown_kpi' is not defined

The style evaluation is now skipped when the cell value is itself in error, since that error is already reported in the cell, and a DataError coming from the style expression is reported with its actual message. style_name is also initialised, as it was left unbound if mis_safe_eval ever raised.

No preliminary issue was opened, as the change is small and self-contained.

Test

mis_builder/tests/test_style_expression.py is added in a separate commit (e6dd781) so the bug can be reproduced before the fix. On that commit the three tests fail:

    FAIL: TestStyleExpression.test_style_expression_of_requeued_kpi
    AssertionError: Unexpected logs found: ["ERROR:...kpimatrix:Style '' not found."]
    FAIL: TestStyleExpression.test_style_expression_error
    AssertionError: 2 != 1
    FAIL: TestStyleExpression.test_style_expression_not_found
    AssertionError: 2 != 1

With the fix applied the full module suite is green (122 tests, 0 failed).

Target branch

19.0, where the bug is. The "Target branch" section of the PR template is out of date: it still refers to versions 9 to 12 and asks to target 10.0.

CLA

Signed.

Changelog entry

mis_builder/readme/newsfragments/830.bugfix, included in the fix commit.

[oca-cla-bot]

All commit authors signed the Contributor License Agreement.

[OCA-git-bot]

Hi @sbidoul,
some modules you are maintaining are being modified, check this out!