From 903e962dc01ecca8651e5251a63814ddc65727a5 Mon Sep 17 00:00:00 2001
From: SirOlaf <34164198+SirOlaf@users.noreply.github.com>
Date: Wed, 9 Sep 2026 14:26:56 +0200
Subject: [PATCH] Attempt at speeding up CI (#26084)

Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
---
 testament/categories.nim |  9 ++++++++-
 testament/specs.nim      |  6 +++++-
 testament/testament.nim  | 29 ++++++++++++++++++++++++++++-
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/testament/categories.nim b/testament/categories.nim
index 6e60d2595c..980a3f529c 100644
--- a/testament/categories.nim
+++ b/testament/categories.nim
@@ -592,10 +592,17 @@ proc changedModuleCount(changed: seq[string]): int =
 
 proc runMetamorphicIcTest(r: var TResults; file: string; cat: Category; options: string) =
   var test = TTest(cat: cat, name: file, options: options,
-                   spec: initSpec(file), startTime: epochTime())
+                   spec: parseSpec(file), startTime: epochTime())
   test.spec.targets = {targetC}
   inc r.total
 
+  # Metamorphic tests bypass `testSpec`, so honour Testament's batch selection
+  # here before creating their build directory or invoking `nim ic`.
+  if not test.spec.inCurrentBatch:
+    finishTest(r, test, targetC, "", "", "", reDisabled)
+    inc r.skipped
+    return
+
   # Absolute paths: `nim ic` runs with `workingDir = buildDir`, so a relative
   # `--nimcache` would resolve against the build dir, not where we read it back.
   let buildDir = (file.changeFileExt("") & "_mm").absolutePath
diff --git a/testament/specs.nim b/testament/specs.nim
index 11b21c2a64..3c44a2fa54 100644
--- a/testament/specs.nim
+++ b/testament/specs.nim
@@ -314,7 +314,11 @@ proc initSpec*(filename: string): TSpec =
 
 proc isCurrentBatch*(testamentData: TestamentData; filename: string): bool =
   if testamentData.testamentNumBatch != 0:
-    hash(filename) mod testamentData.testamentNumBatch == testamentData.testamentBatch
+    let count = testamentData.testamentNumBatch
+    # String hashes can be negative. Normalize the remainder so every test maps
+    # to one of the non-negative batch indexes instead of silently mapping to
+    # no batch at all.
+    ((hash(filename) mod count) + count) mod count == testamentData.testamentBatch
   else:
     true
 
diff --git a/testament/testament.nim b/testament/testament.nim
index bf2bb87c49..1b02101d01 100644
--- a/testament/testament.nim
+++ b/testament/testament.nim
@@ -803,6 +803,30 @@ else:
 
 include categories
 
+const slowCategoriesFirst = [
+  # `execProcesses` schedules commands in order. Starting the longest categories
+  # first avoids leaving a large category as the tail after the other workers
+  # have gone idle. This approximate order comes from representative CI timings;
+  # exact runtimes vary by platform and batch.
+  "stdlib", "ic", "gc", "async", "misc", "lib", "arc", "js", "system",
+  "errmsgs", "ccgbugs", "megatest", "destructor", "vm", "threads",
+  "parallel", "cpp", "generics", "compilerapi", "iter", "exception",
+  "macros", "niminaction", "compiler", "effects", "types", "views", "tools",
+  "dll", "parser", "yrc", "template", "pragmas"
+]
+
+proc categoryScheduleRank(category: string): int =
+  let normalized = category.normalize
+  result = slowCategoriesFirst.len
+  for i, candidate in slowCategoriesFirst:
+    if normalized == candidate:
+      return i
+
+proc cmpCategorySchedule(a, b: string): int =
+  result = cmp(categoryScheduleRank(a), categoryScheduleRank(b))
+  if result == 0:
+    result = cmp(a, b)
+
 proc loadSkipFrom(name: string): seq[string] =
   result = @[]
   if name.len == 0: return
@@ -922,6 +946,7 @@ proc main() =
       for cat in AdditionalCategories:
         if cat notin cats: cats.add cat
     if useMegatest: cats.add MegaTestCat
+    cats.sort(cmpCategorySchedule)
 
     var cmds: seq[string] = @[]
     for cat in cats:
@@ -938,7 +963,9 @@ proc main() =
         processCategory(r, Category(cati), p.cmdLineRest, testsDir, runJoinableTests = false)
     else:
       addExitProc azure.finalize
-      quit osproc.execProcesses(cmds, {poEchoCmd, poStdErrToStdOut, poUsePath, poParentStreams}, beforeRunEvent = progressStatus)
+      quit osproc.execProcesses(cmds,
+        {poEchoCmd, poStdErrToStdOut, poUsePath, poParentStreams},
+        beforeRunEvent = progressStatus)
   of "c", "cat", "category":
     skips = loadSkipFrom(skipFrom)
     var cat = Category(p.key)