leptos-shadcn-ui/docs/remediation/01-test-coverage-crisis.md

Test Coverage Crisis Remediation

Issue Summary

Severity: 🔴 CRITICAL
Effort: 40-60 hours
Priority: P0 (Block all other work)

Problem Description

Repository claims "100% test coverage" but analysis reveals:

• ~170 actual test assertions across entire codebase
• Majority are assert!(true, "message") placeholders
• No coverage tooling configured (tarpaulin, llvm-cov)
• Tests don't mount components in DOM
• No WASM test execution in CI

Root Cause Analysis

1. Test-Driven Development Theater: Tests written to satisfy CI without validating functionality
2. Missing Test Infrastructure: No proper testing harness for Leptos components
3. No Coverage Enforcement: No gates preventing regression
4. Copy-Paste Testing: Same placeholder patterns across all components

Remediation Steps

Step 1: Audit Current Test Reality (4 hours)

# Count real vs placeholder tests
find packages/leptos -name "*.rs" -type f -exec grep -l "assert!(true" {} \; | wc -l
find packages/leptos -name "*.rs" -type f -exec grep -l "assert_eq!\|assert_ne!" {} \; | wc -l

# Generate coverage baseline
cargo install cargo-llvm-cov
cargo llvm-cov --html --output-dir coverage-report/

Step 2: Fix Core Component Tests (20-30 hours)

Priority components to fix first:

1. Button - Most critical, used everywhere
2. Input - Form foundation
3. Card - Layout foundation
4. Badge - Simple but essential
5. Label - Accessibility critical

Example Real Test (Button):

#[cfg(test)]
mod tests {
    use super::*;
    use leptos::*;
    use wasm_bindgen_test::*;
    
    wasm_bindgen_test_configure!(run_in_browser);
    
    #[wasm_bindgen_test]
    fn button_renders_with_text() {
        mount_to_body(|| {
            view! {
                <Button>"Click me"</Button>
            }
        });
        
        let button = document()
            .query_selector("button")
            .unwrap()
            .unwrap();
            
        assert_eq!(button.text_content().unwrap(), "Click me");
        assert!(button.class_list().contains("bg-primary"));
    }
    
    #[wasm_bindgen_test] 
    fn button_handles_click_events() {
        let clicked = create_rw_signal(false);
        
        mount_to_body(|| {
            view! {
                <Button on_click=move |_| clicked.set(true)>
                    "Click me"
                </Button>
            }
        });
        
        let button = document()
            .query_selector("button")
            .unwrap()
            .unwrap();
            
        button.click();
        assert!(clicked.get());
    }
}

Step 3: Add Coverage Infrastructure (8 hours)

# Add to Cargo.toml [dev-dependencies]
wasm-bindgen-test = "0.3"
web-sys = "0.3"

# Add coverage config
[toolchain]
channel = "nightly"

[env]
RUSTFLAGS = "-C instrument-coverage"

Step 4: CI Integration (4-6 hours)

# Add to CI pipeline
- name: Generate Coverage
  run: |
    cargo install cargo-llvm-cov
    cargo llvm-cov --workspace --lcov --output-path lcov.info
    
- name: Upload Coverage 
  uses: codecov/codecov-action@v3
  with:
    file: lcov.info
    
- name: Coverage Gate
  run: |
    coverage=$(cargo llvm-cov --workspace --summary-only | grep "TOTAL" | awk '{print $10}' | tr -d '%')
    if [ $(echo "$coverage < 80" | bc -l) -eq 1 ]; then
      echo "Coverage $coverage% below 80% threshold"
      exit 1
    fi

Step 5: WASM Test Execution (6 hours)

- name: Install wasm-pack
  run: curl https://rustwasm.github.io/wasm-pack/installer/init.sh -sSf | sh

- name: Run WASM Tests
  run: |
    for package in packages/leptos/*/; do
      cd "$package"
      wasm-pack test --headless --chrome
      cd - 
    done

Success Criteria

• Real coverage report showing actual percentages
• All placeholder assert!(true) tests replaced
• Core 5 components have 80%+ coverage
• WASM tests running in CI
• Coverage gates preventing regression
• Documentation on how to write proper tests

Risk Mitigation

• Risk: Breaking existing functionality while fixing tests

• Mitigation: Fix one component at a time, test in isolation

• Risk: WASM test setup complexity

• Mitigation: Use proven wasm-bindgen-test patterns

• Risk: Performance impact of coverage

• Mitigation: Only run coverage on merge requests, not every push

Dependencies

• Rust 1.70+ for coverage tooling
• Chrome/Firefox for WASM testing
• CI runner with sufficient memory

Owner

Primary: Senior Frontend Engineer with Rust/WASM experience
Secondary: Test Engineer for CI integration
Reviewer: Staff Engineer for architecture validation