MadAppGang / lsp-hover-testing

Skill Content

---
name: lsp-hover-testing
description: Automated LSP hover validation for Dingo transpiler. Use when testing hover functionality, validating position mappings, checking for hover drift, or debugging LSP issues after sourcemap changes.
allowed-tools: Read, Grep, Glob, Bash, Write, Edit
---

# LSP Hover Testing Skill

Automated headless testing of LSP hover functionality for the Dingo transpiler. Replaces manual VS Code hover checks with reproducible, CI-compatible tests.

## When to Use This Skill

- After making changes to sourcemap/position tracking code
- When debugging hover issues reported by users
- To validate that column/line mappings work correctly
- Before committing changes to `pkg/lsp/`, `pkg/sourcemap/`, or `pkg/transpiler/`
- To create regression tests for hover functionality

## Quick Start

```bash
# Build the tools first
go build -o dingo ./cmd/dingo
go build -o editors/vscode/server/bin/dingo-lsp ./cmd/dingo-lsp
go build -o lsp-hovercheck ./cmd/lsp-hovercheck

# Run hover tests
./lsp-hovercheck --spec "ai-docs/hover-specs/*.yaml"

# Verbose output for debugging
./lsp-hovercheck --spec ai-docs/hover-specs/http_handler.yaml --verbose
```

## Spec File Format

Create YAML specs in `ai-docs/hover-specs/`:

```yaml
file: examples/01_error_propagation/http_handler.dingo

cases:
  - id: 1
    line: 55                    # 1-based line number
    token: userID               # Token to hover on
    occurrence: 1               # Which occurrence (default: 1)
    description: "LHS variable"
    expect:
      contains: "var userID string"      # Must contain substring
      # OR
      containsAny:                        # Any of these
        - "var userID"
        - "userID string"
      # OR
      allowAny: true                      # Accept any result (skip assertion)
```

## Assertion Types

| Type | Description | Example |
|------|-------------|---------|
| `contains` | Must contain substring | `contains: "func foo"` |
| `containsAny` | Any of listed substrings | `containsAny: ["func", "method"]` |
| `notContains` | Must not contain | `notContains: "error"` |
| `allowAny` | Skip assertion, just record | `allowAny: true` |

## Output Format

```
http_handler.yaml:
------------------------------------------------------------
1: works
2: works
3: expected "var r", got "func extractUserID..."
4: works

============================================================
Total: 3 passed, 1 failed
```

## Creating New Test Specs

### Step 1: Identify test positions

```bash
# Show line numbers
sed -n '50,70p' examples/01_error_propagation/http_handler.dingo | nl -ba
```

### Step 2: Create spec file

```bash
cat > ai-docs/hover-specs/my_example.yaml << 'EOF'
file: examples/my_example/file.dingo

cases:
  - id: 1
    line: 10
    token: myFunction
    description: "Function name hover"
    expect:
      contains: "func myFunction"
EOF
```

### Step 3: Run and iterate

```bash
./lsp-hovercheck --spec ai-docs/hover-specs/my_example.yaml --verbose
```

## Debugging Failed Tests

When a test fails, check:

1. **Column position**: Is the token found at the right column?
2. **Tab handling**: Lines starting with tabs may have offset issues
3. **Transformed lines**: Error prop lines map to different Go positions
4. **LSP readiness**: Increase `--retries` if hover returns empty

### Verbose debug output

```bash
./lsp-hovercheck --spec ai-docs/hover-specs/http_handler.yaml --verbose
```

Shows:
- Exact LSP request/response JSON
- Computed column positions
- Hover content returned

## Known Limitations

### VS Code vs Automated Differences

The automated test may show different results than VS Code due to:
- Tab character handling differences
- LSP initialization timing
- VS Code extension preprocessing

### Current Behavior (2025-12-14)

| Position Type | Automated Result | VS Code Result |
|--------------|------------------|----------------|
| Function names | Works | Works |
| Function arguments | Works | Shows function sig (bug) |
| LHS variables | Empty | Shows temp var (bug) |

## File Locations

| File | Purpose |
|------|---------|
| `cmd/lsp-hovercheck/` | Hover check tool source |
| `ai-docs/hover-specs/` | Test specification files |
| `editors/vscode/server/bin/dingo-lsp` | LSP server binary |

## CI Integration

Add to your CI pipeline:

```yaml
- name: Build tools
  run: |
    go build -o dingo ./cmd/dingo
    go build -o editors/vscode/server/bin/dingo-lsp ./cmd/dingo-lsp
    go build -o lsp-hovercheck ./cmd/lsp-hovercheck

- name: Run hover tests
  run: ./lsp-hovercheck --spec "ai-docs/hover-specs/*.yaml"
```

## Related Files

- [Spec format reference](SPEC_FORMAT.md)
- [Debugging guide](DEBUGGING.md)