Fix test directory creation: ensure test-output exists before writing

Root cause: The ./test-output/ directory is gitignored, so it doesn't
exist in fresh GitHub Actions checkouts. Tests were trying to write to
this directory without creating it first, causing ENOENT errors.

Solution: Add mkdirSync('./test-output', { recursive: true }) before
each writeFileSync call in all affected test files.

Changes:
- test-latex-export-real.ts: Import mkdirSync, create dir before write
- test-latex-export-maxwell.ts: Import mkdirSync, create dir before write
- test-beamer-export.ts: Import mkdirSync, create dir before write
- test-beamer-export-maxwell.ts: Import mkdirSync, create dir before write
- test-typst-export.ts: Import mkdirSync, create dir before write

The { recursive: true } flag means:
✓ No error if directory already exists
✓ Creates parent directories if needed
✓ Makes tests self-sufficient and runnable anywhere

Verification:
- Deleted local test-output/ directory
- Ran all 5 test scripts
- All passed and created files successfully

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: stared

test-beamer-export-maxwell.ts

@@ -2,7 +2,7 @@
 import { parseContent } from './src/parser';
 import { exportToBeamer } from './src/exporter';
 import type { ColorScheme } from './src/exporter';
-import { writeFileSync, readFileSync } from 'fs';
+import { writeFileSync, readFileSync, mkdirSync } from 'fs';
 
 // Test color scheme - Maxwell has 10 terms
 const colorScheme: ColorScheme = {
@@ -66,6 +66,7 @@ async function testBeamerExport() {
 
   // Write to file for manual inspection
   const outputPath = './test-output/test-maxwell-beamer.tex';
+  mkdirSync('./test-output', { recursive: true });
   writeFileSync(outputPath, beamer);
   console.log(`Beamer output written to: ${outputPath}`);
   console.log('Compile with: pdflatex ./test-output/test-maxwell-beamer.tex');

test-beamer-export.ts

@@ -2,7 +2,7 @@
 import { parseContent } from './src/parser';
 import { exportToBeamer } from './src/exporter';
 import type { ColorScheme } from './src/exporter';
-import { writeFileSync, readFileSync } from 'fs';
+import { writeFileSync, readFileSync, mkdirSync } from 'fs';
 
 // Test color scheme
 const colorScheme: ColorScheme = {
@@ -70,6 +70,7 @@ async function testBeamerExport() {
 
   // Write to file for manual inspection
   const outputPath = './test-output/test-euler-beamer.tex';
+  mkdirSync('./test-output', { recursive: true });
   writeFileSync(outputPath, beamer);
   console.log(`Beamer output written to: ${outputPath}`);
   console.log('Compile with: pdflatex ./test-output/test-euler-beamer.tex');

test-latex-export-maxwell.ts

@@ -2,7 +2,7 @@
 import { parseContent } from './src/parser';
 import { exportToLaTeX } from './src/exporter';
 import type { ColorScheme } from './src/exporter';
-import { writeFileSync, readFileSync } from 'fs';
+import { writeFileSync, readFileSync, mkdirSync } from 'fs';
 
 // Test color scheme - Maxwell has 10 terms
 const colorScheme: ColorScheme = {
@@ -66,6 +66,7 @@ async function testLatexExport() {
 
   // Write to file for manual inspection
   const outputPath = './test-output/test-maxwell.tex';
+  mkdirSync('./test-output', { recursive: true });
   writeFileSync(outputPath, latex);
   console.log(`LaTeX output written to: ${outputPath}`);
   console.log('You can compile it with: pdflatex ./test-output/test-maxwell.tex\n');

test-latex-export-real.ts

@@ -2,7 +2,7 @@
 import { parseContent } from './src/parser';
 import { exportToLaTeX } from './src/exporter';
 import type { ColorScheme } from './src/exporter';
-import { writeFileSync, readFileSync } from 'fs';
+import { writeFileSync, readFileSync, mkdirSync } from 'fs';
 
 // Test color scheme
 const colorScheme: ColorScheme = {
@@ -66,6 +66,7 @@ async function testLatexExport() {
 
   // Write to file for manual inspection
   const outputPath = './test-output/test-euler-export.tex';
+  mkdirSync('./test-output', { recursive: true });
   writeFileSync(outputPath, latex);
   console.log(`LaTeX output written to: ${outputPath}`);
   console.log('You can compile it with: pdflatex ./test-output/test-euler-export.tex\n');

test-typst-export.ts

@@ -2,7 +2,7 @@
 import { parseContent } from './src/parser';
 import { exportToTypst } from './src/exporter';
 import type { ColorScheme } from './src/exporter';
-import { writeFileSync, readFileSync } from 'fs';
+import { writeFileSync, readFileSync, mkdirSync } from 'fs';
 
 // Test color scheme
 const colorScheme: ColorScheme = {
@@ -66,6 +66,7 @@ async function testTypstExport() {
 
   // Write to file for manual inspection
   const outputPath = './test-output/test-euler.typ';
+  mkdirSync('./test-output', { recursive: true });
   writeFileSync(outputPath, typst);
   console.log(`Typst output written to: ${outputPath}`);
   console.log('You can compile it with: typst compile ./test-output/test-euler.typ\n');