Problem

At Stripe, a simple test automation script receives a list of test result strings and must produce a compact summary. Write a function that parses the results, counts each status, and returns the names of failed tests in the order they first appear.

Formal Specification

Implement a function summarize_test_results(results) where results is a list of strings. Each string has the format "<test_name>:<status>", where <status> is one of PASS, FAIL, or SKIP. Return a dictionary with four keys:

• passed: number of tests with status PASS
• failed: number of tests with status FAIL
• skipped: number of tests with status SKIP
• failed_tests: list of unique failed test names in first-seen order

If a test name appears multiple times with status FAIL, include it only once in failed_tests, but count every failed entry in failed.

Examples

Example 1

• Input: results = ["login:PASS", "checkout:FAIL", "search:SKIP", "checkout:FAIL"]
• Output: {"passed": 1, "failed": 2, "skipped": 1, "failed_tests": ["checkout"]}
• Explanation: There are two failed entries, but checkout appears once in the failed test list.

Example 2

• Input: results = ["api:PASS", "ui:PASS"]
• Output: {"passed": 2, "failed": 0, "skipped": 0, "failed_tests": []}
• Explanation: All tests passed, so the failed list is empty.

Constraints

• 0 <= len(results) <= 10^4
• Each string contains exactly one : separator
• Test names are non-empty strings
• Status is always one of PASS, FAIL, or SKIP