Start mutation-checking the scripts/ folder

TODO.md

@@ -1540,6 +1540,20 @@ Starting points: `findMisplacedTests` in `scripts/unit-tests-report-imports.ts`
 (the `test.imports.includes(appEntry)` guard and the `subjects.length !== 1`
 guard), and `SHARED_SETUP_FILES` in `scripts/test-subjects.ts`.
 
+## Split the compact test reporter (from PR #1944 review)
+
+Codex flagged `scripts/compact-test-reporter.ts` at 561 lines, above the ~400
+target. It holds five separate jobs: reading the `deno test` arguments and
+guessing how many tests will run, parsing TAP failure reports, drawing the
+progress bar, printing the run summary, and running the child process.
+
+The tests for it already sit in `test/scripts/compact-test-reporter/` as
+`estimate`, `diagnostics`, `progress`, `reporter` and `summary`, so the source
+can be split into a folder of the same names and each pair stays mirrored (which
+is what the mutation gate wants). Out of scope for #1944, whose job was closing
+the mutation gaps rather than moving the file around; the file scores 100% as it
+stands, so the split can be a pure move.
+
 ---
 
 ## Mutation gaps in `src/shared/crypto/encryption.ts`

scripts/bench/bundle-composition/javascript-ast.ts

@@ -2,13 +2,9 @@ import { parseSync } from "npm:oxc-parser@0.132.0";
 import { map } from "#fp";
 
 const countAstNodes = (root: object): number => {
-  const visited = new WeakSet<object>();
   let count = 0;
   const visit = (value: unknown): void => {
-    if (value === null || typeof value !== "object" || visited.has(value)) {
-      return;
-    }
-    visited.add(value);
+    if (value === null || typeof value !== "object") return;
     if ("type" in value) count += 1;
     map(visit)(Object.values(value));
   };

scripts/check-copy.ts

@@ -5,6 +5,6 @@
  * `deno task precommit`, or on its own with `deno task check:copy`.
  */
 
-import { runCopyCheck } from "./check-copy/run.ts";
+import { CATALOG_DIR, runCopyCheck } from "./check-copy/run.ts";
 
-Deno.exit(runCopyCheck("src/locales/en", console.log, console.error));
+Deno.exit(runCopyCheck(CATALOG_DIR, console.log, console.error));

scripts/check-copy/run.ts

@@ -5,6 +5,8 @@
 
 import { type CopyEntry, findIssues, formatIssue } from "./rules.ts";
 
+export const CATALOG_DIR = "src/locales/en";
+
 /** Read every translatable string from a locale folder's JSON files. */
 export const readCatalog = (dir: string): CopyEntry[] => {
   const entries: CopyEntry[] = [];

scripts/compact-test-reporter.ts

@@ -48,7 +48,7 @@ const PROGRESS_WIDTH = 24;
 const TEST_RESULT_RE = /^\s*(not\s+)?ok\s+\d+(?:\s+-\s+(.*))?$/;
 const PLAN_RE = /^\s*(\d+)\.\.(\d+)(?:\s+#.*)?$/;
 const STEP_FAILURE_RE = /^\d+\s+test\s+steps?\s+failed\.$/;
-const REPORTER_FLAGS = new Set(["--reporter"]);
+/** Deno test flags that take a separate value, which is never a file path. */
 const FILE_ARG_VALUE_FLAGS = new Set([
   "--cert",
   "--config",
@@ -238,9 +238,9 @@ const locationFromStack = (
 ): Location | undefined => {
   const matches = message.match(/file:\/\/[^\s)]+:\d+:\d+/g) ?? [];
   for (const match of matches) {
+    // The pattern ends in :line:column, so both colons are always there.
     const columnSplit = match.lastIndexOf(":");
     const lineSplit = match.lastIndexOf(":", columnSplit - 1);
-    if (lineSplit === -1 || columnSplit === -1) continue;
 
     const url = match.slice(0, lineSplit);
     let file: string;
@@ -263,12 +263,7 @@ const locationFromStack = (
 };
 
 export const hasReporterArg = (args: string[]): boolean =>
-  args.some(
-    (arg, index) =>
-      REPORTER_FLAGS.has(arg) ||
-      arg.startsWith("--reporter=") ||
-      args[index - 1] === "--reporter",
-  );
+  args.some((arg) => arg === "--reporter" || arg.startsWith("--reporter="));
 
 const collectFileArgs = (args: string[]): string[] => {
   const files: string[] = [];
@@ -336,7 +331,7 @@ export const estimateTapEventCount = async (
 
 export class CompactTapReporter {
   #cwd: string;
-  #estimatedTotal?: number | undefined;
+  #estimatedTotal: number;
   #hideProgress: boolean;
   #stdout: (line: string) => void;
   #stderr: (line: string) => void;
@@ -349,7 +344,7 @@ export class CompactTapReporter {
 
   constructor(options: CompactTapReporterOptions) {
     this.#cwd = options.cwd;
-    this.#estimatedTotal = options.estimatedTotal;
+    this.#estimatedTotal = options.estimatedTotal ?? 0;
     this.#hideProgress = options.hideProgress ?? false;
     this.#stdout = options.stdout ?? console.log;
     this.#stderr = options.stderr ?? console.error;
@@ -464,19 +459,19 @@ export class CompactTapReporter {
   }
 
   #growEstimatedTotal(total: number): void {
-    if (!Number.isFinite(total) || total <= 0) return;
-    this.#estimatedTotal = Math.max(this.#estimatedTotal ?? 0, total);
+    if (total <= 0) return;
+    this.#estimatedTotal = Math.max(this.#estimatedTotal, total);
   }
 
+  /** A bar and a count; the total grows whenever the run outruns it. */
   #progress(): string {
     if (this.#hideProgress) return "";
 
+    // A result line is what asks for progress, so at least one test is done
+    // and growing the total by it always leaves a total of one or more.
     const done = this.#passed + this.#failed;
     this.#growEstimatedTotal(done);
     const total = this.#estimatedTotal;
-    if (!total) {
-      return `[${String(done).padStart(4, " ")} done]`;
-    }
 
     const shownDone = Math.min(done, total);
     const fill = Math.min(

scripts/mutation/equivalent-mutants.txt

@@ -928,3 +928,49 @@ scripts/mutation/test-map.ts:119:46  && → ||   # ownedTest gives every integra
 # SumUp client: values that are never falsy apart from null.
 src/shared/sumup.ts:215:18  ?? → ||   # withClient resolves to the callback's `true` or to null on failure, so the only non-null value is truthy and ?? false and || false agree
 src/shared/sumup.ts:254:37  ?? → ||   # settings.sumup.keyMode is typed "test" | "live" | null, so it has no falsy non-null value and ?? "unknown" and || "unknown" agree
+
+# Bundle AST bench: the parser's filename argument is a diagnostic label only.
+scripts/bench/bundle-composition/javascript-ast.ts:17:28  bundle.js → ""   # oxc uses the name only to label diagnostics and to pick a language from its extension; "bundle.js" and "" both select the default JavaScript parser, and the only parser output this module reads is errors[0].message (which never contains the name) and the node count
+
+# Script cleanup: the second length check can never see a single error.
+scripts/cleanup.ts:7:23  1 → 0   # the line above already throws when there is exactly one error, so this check only ever runs with 0 or 2+ errors, where > 1 and > 0 agree
+
+# Compact test reporter: fallbacks for values the regexes always provide, and
+# comparisons an earlier line has already ruled out.
+scripts/compact-test-reporter.ts:85:33  ?? → ||   # /^\s*/ matches every string, so the optional chain always yields a length and the fallback never runs
+scripts/compact-test-reporter.ts:85:37  0 → 1   # same line: the fallback is unreachable because /^\s*/ always matches
+scripts/compact-test-reporter.ts:91:62  0 → 1   # this arm runs only when every line is blank, and slicing 0 or 1 characters off blank lines leaves the same text once the join is trimmed
+scripts/compact-test-reporter.ts:131:35  ?? → ||   # match[2] exists whenever the line matched, and its trimmed value is a string, so ?? "" and || "" agree
+scripts/compact-test-reporter.ts:131:39   → "mutated"   # unreachable fallback: match[2] is always present on a matched line
+scripts/compact-test-reporter.ts:132:33  ?? → ||   # match[1] is the indent capture, always present on a matched line
+scripts/compact-test-reporter.ts:132:37   → "mutated"   # unreachable fallback for the same reason
+scripts/compact-test-reporter.ts:169:58  ?? → ||   # atIndex came from findIndex, so lines[atIndex] is always a string
+scripts/compact-test-reporter.ts:169:62   → "mutated"   # unreachable fallback for the same reason
+scripts/compact-test-reporter.ts:175:31  ?? → ||   # match[1] is one of file/line/column on a matched line, never missing
+scripts/compact-test-reporter.ts:175:35   → "mutated"   # unreachable fallback; an unknown key is ignored by assignAtField either way
+scripts/compact-test-reporter.ts:175:63  ?? → ||   # match[2] is always present on a matched line
+scripts/compact-test-reporter.ts:175:67   → "mutated"   # unreachable fallback for the same reason
+scripts/compact-test-reporter.ts:203:40  ?? → ||   # parseYamlTapDiagnostic returns an object or undefined, so its only falsy value is the undefined the fallback handles
+scripts/compact-test-reporter.ts:208:43  ?? → ||   # diagnostic.message is a string or undefined, and the empty string it can be is the fallback itself
+scripts/compact-test-reporter.ts:208:47   → "mutated"   # neither the empty string nor "mutated" matches the step-failure pattern, so the outcome is the same
+scripts/compact-test-reporter.ts:239:61  ?? → ||   # String.match with a global pattern returns an array or null, and an array is always truthy
+scripts/compact-test-reporter.ts:323:60   → "mutated"   # the fallback text for an unreadable file is only counted for test declarations, and neither the empty string nor "mutated" holds one
+scripts/compact-test-reporter.ts:347:50  ?? → ||   # an estimated total of 0 falls back to 0, so ?? and || pick the same number
+scripts/compact-test-reporter.ts:347:54  0 → 1   # the total is immediately grown to the number of finished tests, which is 1 or more whenever it is read
+scripts/compact-test-reporter.ts:348:46  ?? → ||   # hideProgress is a boolean or undefined, and false falls back to false either way
+scripts/compact-test-reporter.ts:349:34  ?? → ||   # the stdout option is a function when present, and functions are always truthy
+scripts/compact-test-reporter.ts:350:34  ?? → ||   # the stderr option is a function when present, and functions are always truthy
+scripts/compact-test-reporter.ts:384:21  --- → ""   # a line that trims to nothing has already returned above, so comparing the trimmed line with "" is never true
+scripts/compact-test-reporter.ts:384:42  ... → ""   # same line, same reason
+scripts/compact-test-reporter.ts:443:44  ?? → ||   # locationFromStack returns a location object or undefined, and objects are always truthy
+
+# Mutation summary: grouped results are arrays or absent, never falsy-but-set.
+scripts/mutation/summary.ts:65:69  ?? → ||   # Object.groupBy gives each status a non-empty array or nothing at all, and an array is always truthy
+scripts/mutation/summary.ts:92:33  ?? → ||   # the survivors group is an array when present, so ?? [] and || [] pick the same list
+
+# Lock file: the handle exists only to carry the advisory lock.
+scripts/lock-file.ts:4:41  true → false   # nothing ever reads or writes through this handle, so opening it write-only still takes and releases the same lock
+
+# Process helpers: the timer handle before the timer exists.
+scripts/process.ts:60:17  0 → 1   # the promise body runs straight away and overwrites this handle, so its starting value is never the one cleared
+scripts/process.ts:62:12  = → +=   # the handle starts at 0, so adding to it and replacing it store the same timer id