make tests/stdlib tests joinable (#14626)

* make tests/stdlib tests joinable

* fixup

testament/categories.nim

@@ -35,7 +35,6 @@ const
     "niminaction",
     "threads",
     "untestable",
-    "stdlib",
     "testdata",
     "nimcache",
     "coroutines",
@@ -573,6 +572,9 @@ proc isJoinableSpec(spec: TSpec): bool =
     spec.outputCheck != ocSubstr and
     spec.ccodeCheck.len == 0 and
     (spec.targets == {} or spec.targets == {targetC})
+  if result:
+    if spec.file.readFile.contains "when isMainModule":
+      result = false
 
 proc norm(s: var string) =
   while true:
@@ -585,6 +587,13 @@ proc quoted(a: string): string =
   # todo: consider moving to system.nim
   result.addQuoted(a)
 
+proc normalizeExe(file: string): string =
+  # xxx common pattern, should be exposed in std/os, even if simple (error prone)
+  when defined(posix):
+    if file.len == 0: ""
+    elif DirSep in file: file else: "./" & file
+  else: file
+
 proc runJoinedTest(r: var TResults, cat: Category, testsDir: string) =
   ## returns a list of tests that have problems
   var specs: seq[TSpec] = @[]
@@ -620,26 +629,24 @@ proc runJoinedTest(r: var TResults, cat: Category, testsDir: string) =
 
   for i, runSpec in specs:
     let file = runSpec.file
-    let file2 = outDir / ("megatest_" & $i & ".nim")
+    let file2 = outDir / ("megatest_$1.nim" % $i)
     # `include` didn't work with `trecmod2.nim`, so using `import`
-    let code = "echo \"" & marker & "\", " & quoted(file) & "\n"
+    let code = "echo \"$1\", $2\n" % [marker, quoted(file)]
     createDir(file2.parentDir)
     writeFile(file2, code)
-    megatest.add "import " & quoted(file2) & "\n"
-    megatest.add "import " & quoted(file) & "\n"
+    megatest.add "import $1\nimport $2\n" % [quoted(file2), quoted(file)]
 
-  writeFile("megatest.nim", megatest)
-
-  let args = ["c", "--nimCache:" & outDir, "-d:testing", "--listCmd",
-              "--listFullPaths:off", "--excessiveStackTrace:off", "megatest.nim"]
+  let megatestFile = testsDir / "megatest.nim" # so it uses testsDir / "config.nims"
+  writeFile(megatestFile, megatest)
 
+  let root = getCurrentDir()
+  let args = ["c", "--nimCache:" & outDir, "-d:testing", "--listCmd", "--path:" & root, megatestFile]
   var (cmdLine, buf, exitCode) = execCmdEx2(command = compilerPrefix, args = args, input = "")
   if exitCode != 0:
-    echo "$ ", cmdLine
-    echo buf.string
+    echo "$ " & cmdLine & "\n" & buf.string
     quit("megatest compilation failed")
 
-  (buf, exitCode) = execCmdEx("./megatest")
+  (buf, exitCode) = execCmdEx(megatestFile.changeFileExt(ExeExt).normalizeExe)
   if exitCode != 0:
     echo buf.string
     quit("megatest execution failed")
@@ -662,7 +669,7 @@ proc runJoinedTest(r: var TResults, cat: Category, testsDir: string) =
   else:
     echo "output OK"
     removeFile("outputGotten.txt")
-    removeFile("megatest.nim")
+    removeFile(megatestFile)
   #testSpec r, makeTest("megatest", options, cat)
 
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