Swift track testing issue: ListOps TEST 16

voxEko · August 25, 2025, 10:29pm

Hi, The test likely intended to use { $1 / $0 } (element divided by accumulator) instead of { $0 / $1 } (accumulator divided by element).

or

The test writer might have mentally calculated 24 * (1 * 2 * 3 * 4) / (1 * 2 * 3 * 4) but implemented division instead of multiplication.

BNAndras · August 26, 2025, 2:27am

Not at a computer to look closer, but I believe this is the test OP refers to.

github.com

exercism/swift/blob/3c13d7bba58ef40aa9e525a72b6bb5b3b5014575/exercises/practice/list-ops/Tests/ListOpsTests/ListOpsTests.swift#L115


      
            #expect(value == expected)
          }
          
          @Test("direction independent function applied to non-empty list", .enabled(if: RUNALL))
          func testDirectionIndependentFunctionAppliedToNonEmptyList6() {
            let value = ListOps.foldLeft([1, 2, 3, 4], accumulated: 5.0) { $0 + $1 }
            let expected = 15.0
            #expect(value == expected)
          }
          
          @Test("direction dependent function applied to non-empty list", .enabled(if: RUNALL))
          func testDirectionDependentFunctionAppliedToNonEmptyList6() {
            let value = ListOps.foldLeft([1, 2, 3, 4], accumulated: 24.0) { $0 / $1 }
            let expected = 64.0
            #expect(value == expected)
          }
          
          @Test("empty list", .enabled(if: RUNALL))
          func testEmptyList7() {
            let value = ListOps.foldRight([], accumulated: 2.0) { $0 * $1 }
            let expected = 2.0

That test comes from the problem specifications at problem-specifications/exercises/list-ops/canonical-data.json at 689301a30d1a889b52933732e6a9fdc12048a66f · exercism/problem-specifications · GitHub