ci(tests): shard the bats suite 5 ways, not 4, to clear the 30-min macOS cap (#1107)

.github/workflows/tests.yml

@@ -104,7 +104,23 @@ concurrency:
 env:
   # Number of parallel bats shards per OS. The matrix and the shard helper must
   # stay in lockstep; the stable summary job below verifies that they do.
-  SHARD_TOTAL: 4
+  #
+  # 4 -> 5 (#1107 stopgap). The suite grew ~2.85x (788 -> 2246 @tests) since the
+  # partition was tuned, and shard-tests.sh seeds each pinned file at one shard's
+  # AVERAGE share (total_tests/total = 561 now), which over-reserves the two pin
+  # shards and pushes the whole real load onto the non-pin ones: measured 4-shard
+  # @test weights were 281/302/832/831, and macOS 4/4 (831) reached the 30-min
+  # cap while still passing tests. More shards dilutes "the remaining work over
+  # the non-pin shards" (worst-case per non-pin shard = total*(N+2)/N^2: 842 at
+  # N=4, 629 at N=5). N=5 (not 6) because the account runs at most FIVE macOS
+  # jobs at once (see the concurrency header): a 6th macOS shard would queue
+  # behind the other five of its own run, inflating the wall clock past what a
+  # lighter shard buys. Five fits the slots exactly, no self-queue). This does NOT fix the scaling property -- pin_seed still
+  # grows with the suite and the count weight still under-values wait-dominant
+  # files (test_remote 7.5m / test_remote_sync 5.0m / test_watch 3.0m on macOS,
+  # none of them the currently pinned pair) -- tracked in #847 for a real fix
+  # once #1159's per-file timings land.
+  SHARD_TOTAL: 5
   # The Windows legs' sqlite3, pinned three ways (#824).
   #
   # This comment used to end "one trip to chocolatey, which is the only time
@@ -249,7 +265,7 @@ jobs:
     # the required contexts are `bats` (the aggregate) and the Windows install
     # leg, and neither is renamed, so branch protection sees exactly what it
     # saw. `needs` is one of the contexts a job name may read.
-    name: bats (${{ matrix.os }} ${{ matrix.shard }}/4)${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}
+    name: bats (${{ matrix.os }} ${{ matrix.shard }}/5)${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}
     needs: changes
     # Run even if `changes` somehow failed/was skipped — fail open to the full
     # suite rather than leaving this REQUIRED check unreported (which would
@@ -283,7 +299,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        shard: [1, 2, 3, 4]
+        shard: [1, 2, 3, 4, 5]
     steps:
       - uses: actions/checkout@v4
 

tests/test_ci_workflow.bats

@@ -50,7 +50,7 @@
   local workflow="$BATS_TEST_DIRNAME/../.github/workflows/tests.yml"
   # 1. The shard job's name carries the marker, keyed on the docs_only output.
   #    Shard checks are not required contexts, so the name may vary.
-  grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/4)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$workflow"
+  grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/5)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$workflow"
   # 2. The aggregate -- the required context -- keeps its exact name, once,
   #    unconditionally.
   [ "$(grep -c '^    name: bats$' "$workflow")" -eq 1 ]
@@ -72,7 +72,7 @@
   # The mutation took: the marker is gone from the copy.
   if grep -Fq "docs-only, suite skipped' || ''" "$mutant"; then false; fi
   # ...and the name pin no longer matches it.
-  if grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/4)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$mutant"; then false; fi
+  if grep -Fq "name: bats (\${{ matrix.os }} \${{ matrix.shard }}/5)\${{ needs.changes.outputs.docs_only == 'true' && ' — docs-only, suite skipped' || '' }}" "$mutant"; then false; fi
 }
 
 # The suite has to run on the shape that actually gets dogfooded. A PR is only