test(polluter): add polluter bisect script

.gitignore

@@ -39,6 +39,7 @@ yarn-error.log
 testem.log
 /typings
 TESTS-**.xml
+polluter-runner.spec.ts
 
 # System Files
 .DS_Store

package.json

@@ -60,7 +60,8 @@
     "postinstall": "gulp copyGitHooks",
     "cypress:open": "cypress open --config-file=cypress.config.ts",
     "cypress:run": "cypress run --config-file=cypress.config.ts",
-    "serve:ssr:ssr-test": "node dist/ssr-test/server/server.mjs"
+    "serve:ssr:ssr-test": "node dist/ssr-test/server/server.mjs",
+    "polluter:bisect": "node scripts/test-polluter-bisect/test-polluter-bisect.js"
   },
   "private": true,
   "dependencies": {

scripts/test-polluter-bisect/README.md

@@ -0,0 +1,35 @@
+## Description
+Sometimes tests from the `igniteui-angular` project fail when run as part of the full suite, even though they pass when executed in isolation.
+The reason is that some tests pollute the testing environment (e.g. by leaving behind global state or async handles), which causes later tests to behave incorrectly.
+
+With a suite of ~200 test files and more than 5000 tests, it’s not feasible to manually track down the culprit file.
+
+This PR introduces a polluter-bisect script that streamlines the process of identifying polluting tests by:
+- Allowing you to specify a sentinel test file (the test known to fail in polluted environments).
+- Running a binary search over the rest of the suite to narrow down the minimal set of files that trigger the sentinel failure.
+- Supporting two modes:
+  - `before` - only considers tests that run before the sentinel. (default)
+  - `all` - considers all tests in the suite and runs the sentinel last.
+- Providing a flag to optionally skip the initial full-set scan if you already know the sentinel fails in the suite.
+- Generating a temporary polluter-runner spec file to enforce deterministic execution order (bypassing Karma’s automatic sorting).
+
+This makes it possible to isolate polluting test files much faster than running the entire suite repeatedly.
+The script is not intended to run in CI; it’s a developer tool to aid in diagnosing flaky tests.
+
+## Usage
+From the root of the repo, run:
+
+```bash
+# Default: search only in files before the sentinel
+npm run polluter:bisect -- sentinel-file.spec.ts before
+
+# Search across all test files, with sentinel always last
+npm run polluter:bisect -- sentinel-file.spec.ts all
+
+# Skip the initial full-set scan (faster if you already know the sentinel fails in the suite)
+npm run polluter:bisect -- sentinel-file.spec.ts before --skip-initial
+```
+The script will iteratively run subsets of tests until it identifies the polluting test file that causes the sentinel to fail.
+
+>NOTE:
+> In order for the script to work correctly you should set only a single test executor in `projects/igniteui-angular/karma.conf.js` under `parallelOptions`.

scripts/test-polluter-bisect/test-polluter-bisect.js

@@ -0,0 +1,154 @@
+import { spawn } from 'child_process';
+import fs from "fs";
+import path from "path";
+
+main().catch((err) => {
+    console.error(err);
+    process.exit(1);
+})
+
+async function main() {
+    const allFiles = getAllSpecFiles("projects/igniteui-angular/src/lib");
+
+    const sentinelArg = process.argv[2];
+    const mode = process.argv[3] || "before";
+    const skipInitial = process.argv.includes("--skip-initial");
+
+    if (!sentinelArg) {
+        console.error("Usage: node test-polluter-bisect.js <sentinel-file.spec.ts> [before|all]");
+        process.exit(1);
+    }
+
+    const sentinelFile = allFiles.find(f => f.includes(sentinelArg));
+
+    if (!sentinelFile) {
+        console.error(`Sentinel file '${sentinelArg}' not found in the test set.`);
+        process.exit(1);
+    }
+
+    console.log(`Running polluter search with sentinel: ${sentinelArg}, mode: ${mode}`);
+    const culprit = await findPolluter(allFiles, sentinelFile, mode, !skipInitial);
+
+    if (culprit) {
+        console.log(`Polluter file is: ${culprit}`);
+    } else {
+        console.log("No polluter found in the set.");
+    }
+}
+
+async function findPolluter(allFiles, sentinelFile, mode = "before", doInitialScan = true) {
+    let suspects;
+
+    if (mode === "before") {
+        suspects = allFiles.slice(0, allFiles.indexOf(sentinelFile));
+    } else if (mode === "all") {
+        suspects = allFiles.filter(f => f !== sentinelFile);
+    } else {
+        throw new Error(`Unknown mode: ${mode}`);
+    }
+
+    if (doInitialScan) {
+        console.log("Initial run with full set...");
+        const initialPass = await runTests([...suspects, sentinelFile], sentinelFile);
+
+        if (initialPass) {
+            console.log("Sentinel passed even after full set — no polluter detected.");
+            return null;
+        }
+    } else {
+        console.log("Skipping initial full-set scan.");
+    }
+
+    while (suspects.length > 1) {
+        const mid = Math.floor(suspects.length / 2);
+        const left = suspects.slice(0, mid);
+        const right = suspects.slice(mid);
+
+        if (await runTests([...left, sentinelFile], sentinelFile)) {
+            suspects = right;
+        } else {
+            suspects = left;
+        }
+    }
+    return suspects[0];
+}
+
+function runTests(files, sentinelFile) {
+    return new Promise((resolve) => {
+        const sentinelNorm = normalizeForNg(sentinelFile);
+        const runnerFile = createPolluterRunner(files);
+
+        const args = [
+            "test",
+            "igniteui-angular",
+            "--watch=false",
+            "--include",
+            runnerFile
+        ];
+
+        let output = "";
+        let finished = false;
+
+        const finish = (reason) => {
+            if (finished) return;
+            finished = true;
+
+            const sentinelFailed = path.basename(sentinelNorm);
+            const failed = output.includes("FAILED") && output.includes(sentinelFailed);
+            console.log(`Sentinel ${sentinelFailed} ${failed ? "FAILED" : "PASSED"} [via ${reason}]`);
+            resolve(!failed);
+
+            if (!proc.killed) proc.kill();
+        };
+
+        const proc = spawn("npx", ["ng", ...args], { shell: true });
+
+        proc.stdout.on("data", (data) => {
+            const text = data.toString();
+            output += text;
+            process.stdout.write(text);
+
+            if (text.includes("TOTAL:")) {
+                finish("stdout");
+            }
+        });
+        proc.stderr.on("data", (data) => {
+            const text = data.toString();
+            output += text;
+            process.stdout.write(text);
+        });
+
+        proc.on("exit", () => {
+            finish("exit");
+        });
+    })
+}
+
+function getAllSpecFiles(dir) {
+    let files = [];
+    fs.readdirSync(dir).forEach((file) => {
+        const full = path.join(dir, file);
+        if (fs.statSync(full).isDirectory()) {
+            files = files.concat(getAllSpecFiles(full));
+        } else if (file.endsWith(".spec.ts")) {
+            files.push(full);
+        }
+    });
+    return files.sort();
+}
+
+function normalizeForNg(file) {
+    const rel = path.relative(process.cwd(), file);
+    return rel.split(path.sep).join("/");
+}
+
+function createPolluterRunner(files) {
+    const imports = files.map(f =>
+        `require('${normalizeForNg(f).replace(/\.ts$/, "")}');`
+    ).join("\n");
+
+    const runnerPath = path.join(process.cwd(), "projects/igniteui-angular/src/polluter-runner.spec.ts");
+    fs.mkdirSync(path.dirname(runnerPath), { recursive: true});
+    fs.writeFileSync(runnerPath, imports, "utf8");
+    return runnerPath;
+}