Allow passing skipPercent

Currently, the default is 5%.

0 gives you 0% time savings
2.5 gives you 29%
5 gives you 38%
10 gives you 50%
20 gives you 65%

Gulpfile.js

@@ -429,6 +429,7 @@ task("runtests-parallel").flags = {
     "   --workers=<number>": "The number of parallel workers to use.",
     "   --timeout=<ms>": "Overrides the default test timeout.",
     "   --built": "Compile using the built version of the compiler.",
+    "   --skipPercent=<number>": "Skip expensive tests with <percent> chance to miss an edit.",
 };
 
 task("diff", () => exec(getDiffTool(), [refBaseline, localBaseline], { ignoreExitCode: true }));

scripts/build/tests.js

@@ -31,6 +31,7 @@ async function runConsoleTests(runJs, defaultReporter, runInParallel, watchMode,
     const inspect = cmdLineOptions.inspect;
     const runners = cmdLineOptions.runners;
     const light = cmdLineOptions.light;
+    const skipPercent = cmdLineOptions.skipPercent;
     const stackTraceLimit = cmdLineOptions.stackTraceLimit;
     const testConfigFile = "test.config";
     const failed = cmdLineOptions.failed;
@@ -62,8 +63,8 @@ async function runConsoleTests(runJs, defaultReporter, runInParallel, watchMode,
         testTimeout = 400000;
     }
 
-    if (tests || runners || light || testTimeout || taskConfigsFolder || keepFailed) {
-        writeTestConfigFile(tests, runners, light, taskConfigsFolder, workerCount, stackTraceLimit, testTimeout, keepFailed);
+    if (tests || runners || light || testTimeout || taskConfigsFolder || keepFailed || skipPercent) {
+        writeTestConfigFile(tests, runners, light, skipPercent, taskConfigsFolder, workerCount, stackTraceLimit, testTimeout, keepFailed);
     }
 
     const colors = cmdLineOptions.colors;
@@ -158,17 +159,19 @@ exports.cleanTestDirs = cleanTestDirs;
  * @param {string} tests
  * @param {string} runners
  * @param {boolean} light
+ * @param {string} skipPercent
  * @param {string} [taskConfigsFolder]
  * @param {string | number} [workerCount]
  * @param {string} [stackTraceLimit]
  * @param {string | number} [timeout]
  * @param {boolean} [keepFailed]
  */
-function writeTestConfigFile(tests, runners, light, taskConfigsFolder, workerCount, stackTraceLimit, timeout, keepFailed) {
+function writeTestConfigFile(tests, runners, light, skipPercent, taskConfigsFolder, workerCount, stackTraceLimit, timeout, keepFailed) {
     const testConfigContents = JSON.stringify({
         test: tests ? [tests] : undefined,
         runners: runners ? runners.split(",") : undefined,
         light,
+        skipPercent,
         workerCount,
         stackTraceLimit,
         taskConfigsFolder,

src/testRunner/parallel/host.ts

@@ -16,8 +16,6 @@ namespace Harness.Parallel.Host {
         const { fork } = require("child_process") as typeof import("child_process");
         const { statSync, readFileSync } = require("fs") as typeof import("fs");
 
-        const editSkipRate = 0.05
-
         // NOTE: paths for module and types for FailedTestReporter _do not_ line up due to our use of --outFile for run.js
         // tslint:disable-next-line:variable-name
         const FailedTestReporter = require(path.resolve(__dirname, "../../scripts/failed-tests")) as typeof import("../../../scripts/failed-tests");
@@ -194,7 +192,7 @@ namespace Harness.Parallel.Host {
             return `tsrunner-${runner}://${test}`;
         }
 
-        function skipCostlyTests(tasks: Task[], editSkipRate: number) {
+        function skipCostlyTests(tasks: Task[]) {
             if (statSync('.test-cost.json')) {
                 const costs = JSON.parse(readFileSync('.test-cost.json', 'utf8')) as {
                     totalTime: number,
@@ -205,12 +203,12 @@ namespace Harness.Parallel.Host {
                 let skippedTests = new Set<string>();
                 let skippedTime = 0;
                 let i = 0;
-                for (; i < costs.data.length && (skippedEdits / costs.totalEdits) < editSkipRate; i++) {
+                for (; i < costs.data.length && (skippedEdits / costs.totalEdits) < (skipPercent / 100); i++) {
                     skippedEdits += costs.data[i].edits;
                     skippedTime += costs.data[i].time;
                     skippedTests.add(costs.data[i].name);
                 }
-                console.log(`Skipped ${i} expensive tests; estimated time savings of ${(skippedTime / costs.totalTime * 100).toFixed(2)}% with ${(editSkipRate * 100).toFixed(2)}% chance of missing a test.`)
+                console.log(`Skipped ${i} expensive tests; estimated time savings of ${(skippedTime / costs.totalTime * 100).toFixed(2)}% with ${skipPercent.toFixed(2)}% chance of missing a test.`)
                 return tasks.filter(t => !skippedTests.has(t.file));
             }
             else {
@@ -219,7 +217,7 @@ namespace Harness.Parallel.Host {
             }
         }
 
-        function startDelayed(perfData: { [testHash: string]: number } | undefined, totalCost: number, editSkipRate: number) {
+        function startDelayed(perfData: { [testHash: string]: number } | undefined, totalCost: number) {
             console.log(`Discovered ${tasks.length} unittest suites` + (newTasks.length ? ` and ${newTasks.length} new suites.` : "."));
             console.log("Discovering runner-based tests...");
             const discoverStart = +(new Date());
@@ -258,7 +256,7 @@ namespace Harness.Parallel.Host {
             }
             tasks.sort((a, b) => a.size - b.size);
             tasks = tasks.concat(newTasks);
-            tasks = skipCostlyTests(tasks, editSkipRate);
+            tasks = skipCostlyTests(tasks);
             const batchCount = workerCount;
             const packfraction = 0.9;
             const chunkSize = 1000; // ~1KB or 1s for sending batches near the end of a test
@@ -653,6 +651,6 @@ namespace Harness.Parallel.Host {
         }
 
         // tslint:disable-next-line:ban
-        setTimeout(() => startDelayed(perfData, totalCost, editSkipRate), 0); // Do real startup on next tick, so all unit tests have been collected
+        setTimeout(() => startDelayed(perfData, totalCost), 0); // Do real startup on next tick, so all unit tests have been collected
     }
 }

src/testRunner/runner.ts

@@ -63,6 +63,7 @@ let runUnitTests: boolean | undefined;
 let stackTraceLimit: number | "full" | undefined;
 let noColors = false;
 let keepFailed = false;
+let skipPercent = 5;
 
 interface TestConfig {
     light?: boolean;
@@ -76,6 +77,7 @@ interface TestConfig {
     noColors?: boolean;
     timeout?: number;
     keepFailed?: boolean;
+    skipPercent?: number;
 }
 
 interface TaskSet {
@@ -107,6 +109,9 @@ function handleTestConfig() {
         if (testConfig.keepFailed) {
             keepFailed = true;
         }
+        if (testConfig.skipPercent !== undefined) {
+            skipPercent = testConfig.skipPercent;
+        }
 
         if (testConfig.stackTraceLimit === "full") {
             (<any>Error).stackTraceLimit = Infinity;