objectscript-tdd

---
name: objectscript-tdd
tier: core
description: Compile-test-fix loop for ObjectScript development. Use when writing or modifying ObjectScript classes.
license: MIT
metadata:
  version: "1.0.0"
  author: InterSystems Developer Community
  compatibility: objectscript, iris, healthconnect
---

## Purpose

Close the feedback loop: write → compile → fix errors → run tests → fix failures → done.

## Process Flow

1. **Write** the class
2. **Review** — run objectscript-review skill first
3. **Compile** — run the compile command for this project
4. **If compile errors**: read the error, identify the line, fix it. Return to step 3.
5. **Run tests** — run the unit test suite
6. **If test failures**: read the failure message, fix the code or the test. Return to step 3.
7. **Done** when: compiles clean + all tests pass

## Compile Command

Use the objectscript MCP tool when available (check `/mcp`):

```text
iris_doc(mode="put", name="MyPackage.MyClass.cls", content="...", compile=true, namespace="USER")
```

Fallback when MCP is unavailable:

```bash
iris session IRIS -U USER "Do $System.OBJ.Load(\"<ClassName>.cls\",\"ck\")"
```

## Key Principle

Never present code to the user that hasn't compiled. If you can't compile (no IRIS access), flag this explicitly:

> ⚠️ No IRIS connection available — code is unverified. Recommend compiling before use.

A class that compiles clean has not been tested. The compiler does not check that a local is set before it is read, and it cannot check a method name built at runtime. Both of these compile with no error and fail when called:

```objectscript
ClassMethod Total(pA As %Integer, pB As %Integer) As %Integer
{
    Set tSum = pA + pB
    Quit tSun                  // <UNDEFINED> tSun at runtime
}

ClassMethod Dyn() As %String
{
    Quit $CLASSMETHOD("MyPackage.MyClass", "Nope")   // <METHOD DOES NOT EXIST> at runtime
}
```

A literal `..Nope()` is caught at compile time, but a dynamic call is not. Call every method you changed at least once, through `iris_execute` or a test, before you call it done.

## Common Compile Errors and Fixes

| Error                              | Cause                                       | Fix                               |
| ---------------------------------- | ------------------------------------------- | --------------------------------- |
| `#1043: QUIT argument not allowed` | `Quit <val>` inside TRY/CATCH               | Change to `Return <val>`          |
| `<COMMAND>` at runtime             | `Quit <val>` inside a For/While block       | Change to `Return <val>`          |
| `Expected a compilable class`      | Missing `Class` keyword or malformed header | Check class declaration line      |
| `Method does not exist`            | Intra-class call without `..`               | Add `..` prefix                   |
| `<UNDEFINED>` at runtime           | Variable used before SET                    | Initialize variable before use    |
| `Expected white space`             | Missing space after command keyword         | Add space: `Set x=1` not `Setx=1` |

## Related skills

- **objectscript-review** — run before compiling to catch common mistakes early
- **objectscript-unit-test** — writing %UnitTest scaffolding
- **objectscript-coverage** — measuring whether your test suite exercises the code (requires merged toolset)
- **objectscript-debugging** — when a test fails with a runtime error