# Univer Spreadsheet Tdd

> Use when authoring SaC or Facade Migration Pack spreadsheet migrations that need assertion-backed Spreadsheet TDD with assertions.ts and univer sac verify feedback.

- Skill: `majiayu000/univer-spreadsheet-tdd` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add majiayu000/univer-spreadsheet-tdd`
- Raw SKILL.md: https://api.skillmd.com/api/skills/majiayu000/univer-spreadsheet-tdd/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Data & Analytics
- Author: majiayu000 (https://skillmd.com/u/majiayu000)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/majiayu000/univer-spreadsheet-tdd

---


# univer-spreadsheet-tdd

Spreadsheet TDD means developing spreadsheet behavior as SaC source: ordered Facade Migration Packs plus executable `assertions.ts` contracts verified by `univer sac verify`.

Ordinary workbook edits can and should be verification-first, but they are not Spreadsheet TDD. For direct workbook inspection, import/export, bounded edits, preview, or versioning work, use `univer-cli`.

## Operating Contract

- Treat `migrations/` as source and the workbook artifact as generated output.
- Treat each non-trivial migration pack's `assertions.ts` as the workbook-visible contract.
- Do not read `.univer` or `.unv` package internals as assertion evidence.
- Do not claim a SaC migration is complete from `univer sac apply` success alone.
- Completion requires the latest relevant `univer sac verify <workspace> --json` run to report `passed`.
- For non-trivial workbook changes, `passed` must include at least one checked pack and at least one passed assertion for the changed pack. An all-skipped or zero-assertion verify run is not a TDD completion signal.

## Workbook Understanding

Understand a SaC workbook from source first:

1. Read the migration plan when present.
2. Read `migrations/` in ledger order.
3. Read each relevant pack's `assertions.ts`.
4. Build the workbook mental model from Facade operations and executable assertions.
5. Use `univer sac verify` reports as feedback on that model.

SaC migration source and `assertions.ts` are the primary authoring and comprehension surface. The `.univer` or `.unv` artifact is generated output in Spreadsheet TDD.

Auxiliary probes: `inspect`, `pipe out`, and readonly runtime commands are allowed for legacy bootstrap, assertion failure debugging, visible state confirmation, or unclear Facade/runtime behavior. They are not the core workflow and must not become the main source of truth when source and assertions are available.

When a probe reveals useful workbook-visible facts, convert it into migration source, `assertions.ts`, or the plan, then return to `univer sac verify`. Do not claim completion from probe output alone.

When a user provides an existing workbook without SaC source, you may use readonly public commands to discover baseline workbook-visible state. Capture useful facts in the first migration plan, source, or assertions, then resume source-first development once SaC source exists.

## Plan First

Before editing migration source, write a short plan:

1. Requested workbook-visible outcomes.
2. Baseline workbook evidence and final-layout reasoning.
3. Workbook range roles: source data, target output, example/demo result, helper/control input, lookup/reference table, existing output, and preserve-only areas.
4. Ordered Facade Migration Packs needed to deliver the outcomes.
5. Assertion gate for each planned migration, including positive and negative checks.
6. Explicit non-goals for the current migration or pass.

For each relevant range role, decide whether the migration may read it, write it, replace it, or must leave it unchanged. Example/demo ranges may explain layout, formulas, or expected shape, but they are not target output unless the request explicitly says to update that range. Helper/control ranges parameterize the operation and should remain unchanged unless requested.

Use multiple focused migrations when the task has multiple durable workbook intents, such as creating a sheet, loading a data model, adding formulas, and adding review output. Each migration should have one clear rollback boundary and its own assertion gate.

Do not split by individual cells, individual commands, or incidental implementation steps. A single migration is correct when the task has one coherent workbook intent.

## Assertion Contract

Every non-trivial migration pack you create or modify needs an `assertions.ts` in the same pack before handoff. Assert workbook-visible outcomes: sheet existence, used range, representative values, formulas, and other stable user-facing facts.

Derive assertions from the user request, baseline workbook evidence, and final-layout reasoning, not from whatever the migration happened to write. Assertions must cover every explicit workbook-visible effect requested by the user, even when some effect is outside a caller-provided check range.

Assertions must prove workbook range roles, not only target values. Assert representative target outputs and assert that source, helper/control, lookup/reference, example/demo, and preserve-only ranges remain unchanged when the requested change does not allow modifying them. When an example/demo range is used to infer a formula or layout, add assertions that distinguish the real target range from the example range.

For formula-driven work, assert representative calculated values in addition to formulas. Cover first, middle, last, blank, zero, date-boundary, text-boundary, and grouping-boundary cases when those cases affect the requested workbook-visible behavior.

Treat external ranges, answer ranges, or requested output ranges as constraints and inspection windows, not as proof that the top-left cell is the output start or that the range contains the whole contract. If the request involves sorting, filtering, grouping, appending, deleting, reshaping, or "no extra" constraints, assert boundary cells before, inside, and after the affected area so stale headings, shifted output, uncleared tails, overwritten rows, and helper artifacts cannot pass unnoticed.

Negative constraints are first-class assertions or probes. Cover requirements such as no extra headings, no helper sheets, no formatting changes, preserved existing rows, blank columns, cleared tails, or no overwrite when they are workbook-visible.

Exact workbook-visible values are part of the contract. Use normalization for internal reasoning only; assertions and writes must preserve required casing, whitespace, abbreviations, blank-versus-zero semantics, text-versus-number semantics, and display-critical stored values.

Keep assertions small and deterministic. Prefer representative ranges over broad workbook snapshots.

```ts
import { defineAssertions } from "univer:sac/assertions";

export default defineAssertions(({ sheet, range }) => [
  sheet("Revenue").exists(),
  sheet("Revenue").usedRange("A1:C4"),
  range("Revenue!A1:C2").values([
    ["Region", "Q1", "Q2"],
    ["West", 1200, 1400],
  ]),
  range("Revenue!C4").formula("=SUM(C2:C3)"),
]);
```

For exact helper behavior, run `univer help sac assertions`.

## Feedback Loop

After editing source or assertions:

1. Run `univer sac apply <workspace>` when the migration is not yet applied.
2. Run `univer sac verify <workspace> --json`.
3. Read the JSON summary and the referenced `.sac/runs/<run-id>/verify-report.json`.
4. If status is `failed`, inspect failures for pack id, assertion kind, target, expected value, actual value, and first difference when present.
5. Decide whether the migration source is wrong or the assertion expectation is wrong, repair it, then apply or verify again.
6. If status is `error`, treat it as setup failure: fix config, missing target, source validation, bundling, or runtime setup before judging workbook behavior.
7. Repeat until the relevant verification status is `passed`.

If verification passes with skipped packs, mention skipped packs when they are relevant. A changed pack must not be skipped unless the task explicitly excludes assertions.

## Versioning And Checkpoints

Versioning commands support the TDD loop; they are not correctness evidence. `commit` is a checkpoint after verification passes. `reset` is a recovery mechanism for a failed or unwanted attempt. `status` can help explain current workbook state, but passing `univer sac verify <workspace> --json` remains the completion gate.

Versioning success does not replace assertion verification.

## Handoff

Final handoff for a SaC Spreadsheet TDD task must include:

- the migration plan outcome, including any multiple migration sequence actually used
- the final verification command
- the final status
- the `verify-report.json` path
- readonly probes used, if any, and why they were auxiliary
- any relevant skipped packs or explicit assertion-free scope