lint: add initial checks for approaches and articles

src/lint/approaches_and_articles.nim

@@ -49,6 +49,19 @@ proc isConfigMissingOrValid(dir: Path, dk: DirKind): bool =
       if not isValidConfig(j, configPath, dk):
         result = false
 
+func countLinesWithoutCodeFence(s: string, dk: DirKind): int =
+  ## Returns the number of lines in `s`, but:
+  ##
+  ## - excluding lines that open or close a Markdown code fence.
+  ## - including a final line that does not end in a newline character.
+  result = 0
+  if s.len > 0:
+    for line in s.splitLines():
+      if not (line.startsWith("```") and dk == dkArticles):
+        inc result
+    if s[^1] in ['\n', '\l']:
+      dec result
+
 proc isEverySnippetValid(exerciseDir: Path, dk: DirKind): bool =
   result = true
   for dir in getSortedSubdirs(exerciseDir / $dk):
@@ -57,15 +70,11 @@ proc isEverySnippetValid(exerciseDir: Path, dk: DirKind): bool =
       dir / &"snippet.{ext}"
     if fileExists(snippetPath):
       let contents = readFile(snippetPath)
-      var numLines = 0
-      for line in contents.splitLines():
-        if not (line.startsWith("```") and dk == dkArticles):
-          inc numLines
-      dec numLines # Allow 8 lines with a final newline.
-      const maxNumLines = 8
-      if numLines > maxNumLines:
+      const maxLines = 8
+      let numLines = countLinesWithoutCodeFence(contents, dk)
+      if numLines > maxLines:
         let msg = &"The file is {numLines} lines long, but it must be at " &
-                  &"most {maxNumLines} lines long"
+                  &"most {maxLines} lines long"
         result.setFalseAndPrint(msg, snippetPath)
 
 proc isEveryApproachAndArticleValid*(trackDir: Path): bool =

tests/test_lint.nim

@@ -1,5 +1,6 @@
-import std/unittest
+import std/[strutils, unittest]
 import "."/lint/validators
+import "."/lint/approaches_and_articles {.all.}
 
 proc testIsKebabCase =
   suite "isKebabCase":
@@ -279,11 +280,77 @@ proc testIsFilesPattern =
         isFilesPattern("somedir/%{pascal_slug}/%{snake_slug}.suffix")
         isFilesPattern("%{pascal_slug}/filename.suffix")
 
+proc testCountLinesWithoutCodeFence =
+  suite "countLinesWithoutCodeFence":
+    test "without code fence":
+      const dk = dkArticles
+      check:
+        countLinesWithoutCodeFence("", dk) == 0
+        countLinesWithoutCodeFence("a", dk) == 1
+        countLinesWithoutCodeFence("a\n", dk) == 1
+        countLinesWithoutCodeFence("foo\n", dk) == 1
+        countLinesWithoutCodeFence("foo\nb", dk) == 2
+        countLinesWithoutCodeFence("foo\nbar", dk) == 2
+        countLinesWithoutCodeFence("foo\nbar\n", dk) == 2
+        countLinesWithoutCodeFence("foo\nbar\nfoo", dk) == 3
+
+    test "with code fence only":
+      const s = """
+        ```nim
+        echo "foo"
+        ```""".unindent()
+      check:
+        countLinesWithoutCodeFence(s, dkArticles) == 1
+        countLinesWithoutCodeFence(s, dkApproaches) == 3
+
+    test "with code fence at start":
+      const s = """
+        ```nim
+        echo "foo"
+        ```
+
+      Some content.
+      """.unindent()
+      check:
+        countLinesWithoutCodeFence(s, dkArticles) == 3
+        countLinesWithoutCodeFence(s, dkApproaches) == 5
+
+    test "with code fence at end":
+      const s = """
+        # Some header
+
+        Some content.
+
+        ```nim
+        echo "foo"
+        ```
+      """.unindent()
+      check:
+        countLinesWithoutCodeFence(s, dkArticles) == 5
+        countLinesWithoutCodeFence(s, dkApproaches) == 7
+
+    test "with code fence in middle":
+      const s = """
+        # Some header
+
+        Some content.
+
+        ```nim
+        echo "foo"
+        ```
+
+        Some content.
+      """.unindent()
+      check:
+        countLinesWithoutCodeFence(s, dkArticles) == 7
+        countLinesWithoutCodeFence(s, dkApproaches) == 9
+
 proc main =
   testIsKebabCase()
   testIsUuidV4()
   testExtractPlaceholders()
   testIsFilesPattern()
+  testCountLinesWithoutCodeFence()
 
 main()
 {.used.}