{
  "id": 11012343,
  "title": "The Test Data I Did Not Write",
  "url": "https://urgent.news/2026/09/30/the-test-data-i-did-not-write",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-09-30T19:19:22.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/remuslazar/the-test-data-i-did-not-write-1chd"
  },
  "original_language": "en",
  "account": "In July, a reporter noticed discrepancies in the charging map, with two pins appearing where one should have existed. The map pulls data from various sources, including the German federal register, roaming networks, and Tesla. The process of selecting the correct listing is executed nightly, and this specific job had been running for fourteen months. It underwent twenty changes, with the most recent one, a refactor in May, being faster and using less memory. The refactor was successful, writing fifteen tests that agreed with the code. However, the tests did not reflect the real-world scenario as the operator names in the test fixtures always matched, whereas in reality, they matched only once out of 9,269 pairs of duplicates. This discrepancy went unnoticed because the test data was not derived from real data, but rather from assumptions made by the developers. The refactor was merged without a review, but the reporter believes the flaw was not caught during the code review due to its hidden nature. The reporter emphasizes the importance of testing the concept with real data rather than relying on test fixtures that do not represent the actual situation. The reporter also highlights the significance of reviewing code changes, asking for a plan, and focusing on small steps. By reading through the code and understanding its behavior, the reporter ensures a more thorough review process.",
  "summary": "In July I was looking at our charging map and saw two pins where there should have been one. Same charging site, a few metres apart, two listings. I zoomed out and found another. Then another. This should not happen. Our map pulls charging stations from several sources: the German federal register, the roaming networks, Tesla. The same physical site often appears in more than one of them, and a…",
  "key_points": [
    "Two charging pins appeared where one should have existed.",
    "Tests written with assumptions, not real data.",
    "Code review emphasized for thorough verification."
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}