testament: fix #16829, fix partially #16830 (#16831)

* fix #16829
* address comments

testament/testament.nim

@@ -54,6 +54,13 @@ On Azure Pipelines, testament will also publish test results via Azure Pipelines
 provided that System.AccessToken is made available via the environment variable SYSTEM_ACCESSTOKEN.
 """ % resultsFile
 
+proc isNimRepoTests(): bool =
+  # this logic could either be specific to cwd, or to some file derived from
+  # the input file, eg testament r /pathto/tests/foo/tmain.nim; we choose
+  # the former since it's simpler and also works with `testament all`.
+  let file = "testament"/"testament.nim.cfg"
+  result = file.fileExists
+
 type
   Category = distinct string
   TResults = object
@@ -86,6 +93,11 @@ var targetsSet = false
 
 proc isSuccess(input: string): bool =
   # not clear how to do the equivalent of pkg/regex's: re"FOO(.*?)BAR" in pegs
+  # note: this doesn't handle colors, eg: `\e[1m\e[0m\e[32mHint:`; while we
+  # could handle colors, there would be other issues such as handling other flags
+  # that may appear in user config (eg: `--listFullPaths`).
+  # Passing `XDG_CONFIG_HOME= testament args...` can be used to ignore user config
+  # stored in XDG_CONFIG_HOME, refs https://wiki.archlinux.org/index.php/XDG_Base_Directory
   input.startsWith("Hint: ") and input.endsWith("[SuccessX]")
 
 proc getFileDir(filename: string): string =
@@ -744,7 +756,8 @@ proc main() =
       let cat = dir[testsDir.len .. ^1]
       if kind == pcDir and cat notin ["testdata", "nimcache"]:
         cats.add cat
-    cats.add AdditionalCategories
+    if isNimRepoTests():
+      cats.add AdditionalCategories
     if useMegatest: cats.add MegaTestCat
 
     var cmds: seq[string]