added a test for 'nim doc'

nimdoc/tester.nim

@@ -0,0 +1,29 @@
+# Small program that runs the test cases for 'nim doc'.
+
+import strutils, os
+
+var
+  failures = 0
+
+proc test(dir: string; fixup = false) =
+  putEnv("SOURCE_DATE_EPOCH", "100000")
+  if execShellCmd("nim doc --project -o:$1/htmldocs $1/testproject.nim" % dir) != 0:
+    quit("FAILURE: nim doc failed")
+
+  for expected in walkDirRec(dir / "expected/"):
+    let produced = expected.replace("/expected/", "/htmldocs/")
+    if not fileExists(produced):
+      echo "FAILURE: files not found: ", produced
+      inc failures
+    elif readFile(expected) != readFile(produced):
+      echo "FAILURE: files differ: ", produced
+      discard execShellCmd("diff -uNdr " & expected & " " & produced)
+      inc failures
+      if fixup:
+        copyFile(produced, expected)
+    else:
+      echo "SUCCESS: files identical: ", produced
+  removeDir(dir / "htmldocs")
+
+test("nimdoc/testproject", false)
+if failures > 0: quit($failures & " failures occurred.")