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- use-generateguid-for-unique-test-fixture-values.md/.good.al: documented each LibraryUtility helper's actual behavior, verified against LibraryUtility.Codeunit.al. GenerateRandomCode opens the target table as a temporary RecordRef, so despite taking TableNo it never checks real data. GenerateRandomXMLText performs no table lookup at all. Only GenerateRandomCodeWithLength/GenerateRandomCode20 (capped at Code[10]/ Code[20]) genuinely verify against the real table. Fixture switched to GenerateRandomCodeWithLength where the comment claims verified uniqueness. - al-testing-review.md: rewired the cue to catch the actual anti-pattern (hardcoded literals, hand-built uniqueness, short-field GUID truncation) instead of only matching the compliant GenerateGUID()+CopyStr shape; broadened tokens to include TestPage, Library - Utility, and .Visible()/.Enabled()/.Editable(). - al-data-modeling-review.md: restricted the Item Ledger Entry Last-Shipping-No. cue to sales combined posting; purchase combined posting is Receive+Invoice and uses different fields entirely. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Generate unique test fixture values with LibraryUtility helpers, not hardcoded literals
Description
A fixture helper that assigns a hardcoded literal to a primary-key or descriptive field collides the moment two tests, or two runs of the same test, create that fixture without cleanup, and a literal longer than the field allows raises a truncation or insert error. LibraryUtility.GenerateGUID() is not a real GUID — it is a Code[10] number-series value (GU00000000–GU99999999) — and it returns the full 10 characters unshortened. Truncating it yourself with CopyStr(..., 1, MaxStrLen(ShorterField)) for a field under 10 characters is unsafe: the changing digits sit at the right end and are exactly what gets cut off, so consecutive calls into a short field can produce the same truncated value. GenerateGUID() is only safe as-is for a field that holds the full 10 characters.
Best Practice
For a field that holds the full 10 characters, assign LibraryUtility.GenerateGUID() directly. For a shorter field, do not truncate a GUID yourself — but also do not assume every LibraryUtility helper verifies uniqueness against the real table, because they don't all behave the same way:
GenerateRandomCode(FieldNo, TableNo)opens the target table as a temporaryRecordRef, so its own emptiness check never inspects real rows — despite takingTableNo, it does not verify against the actual table. It's safe to use for its non-colliding-within-a-single-test-run value (derived fromGenerateGUID()'s own number series), not for a guarantee against pre-existing or leftover data.GenerateRandomCodeWithLength(FieldNo, TableNo, CodeLength)opens the real (non-temporary) table and loops until the generated value doesn't collide — a genuine verified-unique guarantee — but it returnsCode[10]regardless of the requestedCodeLength, so it's only useful for a field of 10 characters or fewer.GenerateRandomCode20(FieldNo, TableNo)is the same real, verified-against-the-table pattern asGenerateRandomCodeWithLength, sized for aCode[20]field.GenerateRandomXMLText(Length)performs no table lookup at all — it's a plain random-text generator, appropriate for a descriptive/incidental field where uniqueness doesn't matter, not for a value that needs to be collision-checked.
Pick GenerateRandomCodeWithLength/GenerateRandomCode20 when the test genuinely needs a code verified unique against the table; use GenerateRandomCode/GenerateGUID/GenerateRandomXMLText for incidental values where a low collision chance is enough.
See sample: use-generateguid-for-unique-test-fixture-values.good.al.
Anti Pattern
Hardcoding a fixture value such as 'TEST001' or a short descriptive literal, which collides across parallel or repeated test runs. Equally an anti-pattern: truncating GenerateGUID()'s result with CopyStr(..., 1, MaxStrLen(Field)) for a field shorter than 10 characters — the truncation removes the part of the value that actually varies.
See sample: use-generateguid-for-unique-test-fixture-values.bad.al.