lint: require some arrays to have unique items (#296)

With this commit, `configlet lint` now checks that the value of each of
the below keys is an array with distinct elements.

Track config:
- `exercises.concept.concepts`
- `exercises.concept.prerequisites`
- `exercises.practice.practices`
- `exercises.practice.prerequisites`

Concept Exercise config:
- `authors`
- `contributors`
- `forked_from`

Practice Exercise config:
- `authors`
- `contributors`

src/lint/concept_exercises.nim

@@ -17,10 +17,12 @@ proc isValidConceptExerciseConfig(data: JsonNode, path: Path): bool =
   if isObject(data, "", path):
     let checks = [
       hasString(data, "blurb", path, maxLen = 350),
-      hasArrayOfStrings(data, "authors", path),
-      hasArrayOfStrings(data, "contributors", path, isRequired = false),
+      hasArrayOfStrings(data, "authors", path, uniqueValues = true),
+      hasArrayOfStrings(data, "contributors", path, isRequired = false,
+                        uniqueValues = true),
       hasValidFiles(data, path),
-      hasArrayOfStrings(data, "forked_from", path, isRequired = false),
+      hasArrayOfStrings(data, "forked_from", path, isRequired = false,
+                        uniqueValues = true),
       hasString(data, "language_versions", path, isRequired = false),
       hasString(data, "icon", path, isRequired = false, checkIsKebab = true),
     ]

src/lint/practice_exercises.nim

@@ -18,8 +18,10 @@ proc isValidPracticeExerciseConfig(data: JsonNode, path: Path): bool =
     # TODO: Enable the `files` checks after the tracks have had some time to update.
     let checks = [
       hasString(data, "blurb", path, maxLen = 350),
-      hasArrayOfStrings(data, "authors", path, isRequired = false),
-      hasArrayOfStrings(data, "contributors", path, isRequired = false),
+      hasArrayOfStrings(data, "authors", path, isRequired = false,
+                        uniqueValues = true),
+      hasArrayOfStrings(data, "contributors", path, isRequired = false,
+                        uniqueValues = true),
       if false: hasValidFiles(data, path) else: true,
       hasString(data, "language_versions", path, isRequired = false),
     ]

src/lint/track_config.nim

@@ -81,9 +81,11 @@ proc isValidConceptExercise(data: JsonNode; context: string; path: Path): bool =
       hasString(data, "uuid", path, context, checkIsUuid = true),
       hasBoolean(data, "deprecated", path, context, isRequired = false),
       hasArrayOfStrings(data, "concepts", path, context,
-                        allowedArrayLen = 0..int.high, checkIsKebab = true),
+                        allowedArrayLen = 0..int.high, checkIsKebab = true,
+                        uniqueValues = true),
       hasArrayOfStrings(data, "prerequisites", path, context,
-                        allowedArrayLen = 0..int.high, checkIsKebab = true),
+                        allowedArrayLen = 0..int.high, checkIsKebab = true,
+                        uniqueValues = true),
       hasString(data, "status", path, context, isRequired = false,
                 allowed = statuses),
     ]
@@ -99,9 +101,11 @@ proc isValidPracticeExercise(data: JsonNode; context: string;
       hasBoolean(data, "deprecated", path, context, isRequired = false),
       hasInteger(data, "difficulty", path, context, allowed = 0..10),
       hasArrayOfStrings(data, "practices", path, context,
-                        allowedArrayLen = 0..int.high, checkIsKebab = true),
+                        allowedArrayLen = 0..int.high, checkIsKebab = true,
+                        uniqueValues = true),
       hasArrayOfStrings(data, "prerequisites", path, context,
-                        allowedArrayLen = 0..int.high, checkIsKebab = true),
+                        allowedArrayLen = 0..int.high, checkIsKebab = true,
+                        uniqueValues = true),
       hasString(data, "status", path, context, isRequired = false,
                 allowed = statuses),
     ]