Data-Driven Testing with Regex Validation — Patterns & Pitfalls

2026-07-17 · By Avinash Kamble, reviewed by Priyanka G.

Data-driven tests scale when the validation rule is expressed as a regex per column. Here's how to wire that up cleanly.

columns.yaml
email: "^[\w.+-]+@[\w-]+\.[\w.-]+$"
phone: "^\+[1-9]\d{1,14}$"
zip:   "^\d{5}$"

for (const row of csv) {
  for (const [col, pattern] of Object.entries(rules)) {
    test(`${col} valid for ${row.id}`, () => {
      expect(row[col]).toMatch(new RegExp(pattern));
    });
  }
}

• Anchors matter. Without ^ and $, "abc@def.com whatever" will pass an email regex.
• Escape user input before compiling into a bigger pattern.
• Compile once, reuse many times — RegExp compilation is expensive at scale.
• Watch for catastrophic backtracking in nested quantifiers.

Paste a column of sample values into the Regex Tester for QA, tweak the pattern until every row matches, then commit it to your rules file.