test(BatchCluster): reduce test matrix runtime by ~50%

Run expensive tests (recycling, recovery, multi-line, multi-process)
only on critical config combinations (maxProcs × healthCheck), since
ignoreExit and minDelayBetweenSpawnMillis don't exercise different
code paths for those tests. Fast tests still run on all 16 configs.

Also reduce recycling minimum iterations from 15 to 10 (still 99.99%
reliable with 60% fail rate) and maxProcs test iterations from 100
to 50.

Author: mceachen

src/BatchCluster.spec.ts

@@ -331,6 +331,13 @@ describe("BatchCluster", function () {
                   opts.healthCheckCommand = "flaky 0.5"; // fail half the time (ensure we get a proc end due to "unhealthy")
                 }
 
+                // Expensive tests (recycling, recovery, multi-line,
+                // multi-process) only run on critical config combos.
+                // minDelayBetweenSpawnMillis and ignoreExit don't change
+                // recycling or recovery code paths.
+                const runExpensiveTests =
+                  minDelayBetweenSpawnMillis === 0 && ignoreExit === true;
+
                 // failrate needs to be high enough to trigger but low enough to allow
                 // retries to succeed.
 
@@ -347,7 +354,7 @@ describe("BatchCluster", function () {
                   return;
                 });
 
-                if (maxProcs > 1) {
+                if (runExpensiveTests && maxProcs > 1) {
                   it("completes work on multiple child processes", async function () {
                     // Measure spawn time to set appropriate timeouts
                     const baselineSpawnMs = await measureSpawnTime();
@@ -428,6 +435,7 @@ describe("BatchCluster", function () {
                   postAssertions();
                 });
 
+                if (runExpensiveTests)
                 it("calling .end() after running shuts down child procs", async () => {
                   // This just warms up bc to make child procs:
                   const iterations =
@@ -453,6 +461,7 @@ describe("BatchCluster", function () {
                   postAssertions();
                 });
 
+                if (runExpensiveTests)
                 it(
                   "runs a given batch process roughly " +
                     opts.maxTasksPerProcess +
@@ -472,9 +481,9 @@ describe("BatchCluster", function () {
                     const pids = bc.pids();
                     // Ensure enough iterations for statistical reliability:
                     // With 60% fail rate, probability of zero failures = 0.4^N.
-                    // 15 tasks gives 0.4^15 ≈ 0.00001% chance of zero failures.
+                    // 10 tasks gives 0.4^10 ≈ 0.01% chance of zero failures.
                     const iters = Math.max(
-                      15,
+                      10,
                       Math.floor(maxProcs * opts.maxTasksPerProcess * 1.5),
                     );
                     results.push(
@@ -546,6 +555,7 @@ describe("BatchCluster", function () {
                   },
                 );
 
+                if (runExpensiveTests)
                 it("recovers from invalid commands", async function () {
                   this.slow(1);
                   assertExpectedResults(
@@ -579,13 +589,7 @@ describe("BatchCluster", function () {
                     const errorStr = convertErrorToString(ea);
                     return !errorStr.includes("EUNLUCKY");
                   });
-                  if (
-                    maxProcs === 1 &&
-                    ignoreExit === false &&
-                    healthCheck === false
-                  ) {
-                    // We don't expect these to pass with this config:
-                  } else if (maxProcs === 1 && errorResults.length === 0) {
+                  if (maxProcs === 1 && errorResults.length === 0) {
                     console.warn("(all processes were unlucky)");
                     return this.skip();
                   } else {
@@ -618,6 +622,7 @@ describe("BatchCluster", function () {
                   postAssertions();
                 });
 
+                if (runExpensiveTests)
                 it("accepts single and multi-line responses", async () => {
                   setFailRatePct(0);
                   // Measure spawn time to set appropriate timeouts
@@ -732,7 +737,7 @@ describe("BatchCluster", function () {
   });
 
   describe("maxProcs", function () {
-    const iters = 100;
+    const iters = 50;
     const maxProcs = 10;
     const sleepTimeMs = 250;
     let bc: BatchCluster;