refactor: deduplicate 5 commonly repeated functions

This consolidates duplicate functions that were scattered across the codebase:

1. **Platform detection functions** (isWindows, isLinux, isMacOS, isPosix)
   - Created internal/platform.ts module for built-in JS modules
   - Updated test files to import from harness instead of redefining

2. **Patch test snapshot normalization**
   - Created harness-patch.ts for shared normalizeBunSnapshotForPatch
   - Consolidated identical implementations from 2 test files

3. **Removed inline isLinux redefinition**
   - net.ts was defining isLinux twice, now uses shared import

Files affected:
- src/js/internal/platform.ts (new shared module)
- src/js/internal/fs/glob.ts (use shared isWindows)
- src/js/node/net.ts (use shared isWindows and isLinux)
- test/harness-patch.ts (new shared test utility)
- test/cli/install/bun-install-patch.test.ts
- test/regression/issue/patch-bounds-check.test.ts
- test/js/node/test/common/index.js
- test/napi/node-napi-tests/test/common/index.js

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/js/internal/fs/glob.ts

@@ -1,8 +1,7 @@
 import type { GlobScanOptions } from "bun";
 const { validateObject, validateString, validateFunction, validateArray } = require("internal/validators");
 const { sep } = require("node:path");
-
-const isWindows = process.platform === "win32";
+const { isWindows } = require("internal/platform");
 
 interface GlobOptions {
   /** @default process.cwd() */

src/js/internal/platform.ts

@@ -0,0 +1,16 @@
+/**
+ * Internal platform detection utilities
+ * Used by built-in modules to check the current platform
+ */
+
+const isWindows = process.platform === "win32";
+const isMacOS = process.platform === "darwin";
+const isLinux = process.platform === "linux";
+const isPosix = isMacOS || isLinux;
+
+export default {
+  isWindows,
+  isMacOS,
+  isLinux,
+  isPosix,
+};

src/js/node/net.ts

@@ -39,7 +39,7 @@ const ArrayPrototypePush = Array.prototype.push;
 const MathMax = Math.max;
 
 const { UV_ECANCELED, UV_ETIMEDOUT } = process.binding("uv");
-const isWindows = process.platform === "win32";
+const { isWindows, isLinux } = require("internal/platform");
 
 const getDefaultAutoSelectFamily = $zig("node_net_binding.zig", "getDefaultAutoSelectFamily");
 const setDefaultAutoSelectFamily = $zig("node_net_binding.zig", "setDefaultAutoSelectFamily");
@@ -2272,7 +2272,6 @@ Server.prototype.listen = function listen(port, hostname, onListen) {
         port = 0;
       }
 
-      const isLinux = process.platform === "linux";
 
       if (!Number.isSafeInteger(port) || port < 0) {
         if (path) {

test/cli/install/bun-install-patch.test.ts

@@ -1,15 +1,9 @@
 import { $ } from "bun";
 import { beforeAll, describe, expect, it, setDefaultTimeout, test } from "bun:test";
-import { bunEnv, bunExe, normalizeBunSnapshot as normalizeBunSnapshot_, tempDirWithFiles } from "harness";
+import { bunEnv, bunExe, tempDirWithFiles } from "harness";
+import { normalizeBunSnapshotForPatch as normalizeBunSnapshot } from "../../harness-patch";
 import { join } from "path";
 
-const normalizeBunSnapshot = (str: string) => {
-  str = normalizeBunSnapshot_(str);
-  str = str.replace(/.*Resolved, downloaded and extracted.*\n?/g, "");
-  str = str.replaceAll("fstatat()", "stat()");
-  return str;
-};
-
 beforeAll(() => {
   setDefaultTimeout(1000 * 60 * 5);
 });

test/harness-patch.ts

@@ -0,0 +1,12 @@
+import { normalizeBunSnapshot as normalizeBunSnapshotBase } from "./harness";
+
+/**
+ * Normalize Bun snapshot output for patch-related tests
+ * Removes package resolution messages and normalizes fstatat() to stat()
+ */
+export const normalizeBunSnapshotForPatch = (str: string) => {
+  str = normalizeBunSnapshotBase(str);
+  str = str.replace(/.*Resolved, downloaded and extracted.*\n?/g, "");
+  str = str.replaceAll("fstatat()", "stat()");
+  return str;
+};

test/js/node/test/common/index.js

@@ -159,12 +159,10 @@ if (process.argv.length === 2 &&
   }
 }
 
-const isWindows = process.platform === 'win32';
+const { isWindows, isLinux, isMacOS } = require('../../../harness');
 const isSunOS = process.platform === 'sunos';
 const isFreeBSD = process.platform === 'freebsd';
 const isOpenBSD = process.platform === 'openbsd';
-const isLinux = process.platform === 'linux';
-const isMacOS = process.platform === 'darwin';
 const isASan = process.config.variables.asan === 1;
 const isRiscv64 = process.arch === 'riscv64';
 const isDebug = process.features.debug;

test/napi/node-napi-tests/test/common/index.js

@@ -136,12 +136,10 @@ if (process.argv.length === 2 &&
   }
 }
 
-const isWindows = process.platform === 'win32';
+const { isWindows, isLinux, isMacOS } = require('../../../../harness');
 const isSunOS = process.platform === 'sunos';
 const isFreeBSD = process.platform === 'freebsd';
 const isOpenBSD = process.platform === 'openbsd';
-const isLinux = process.platform === 'linux';
-const isMacOS = process.platform === 'darwin';
 const isASan = process.config.variables.asan === 1;
 const isRiscv64 = process.arch === 'riscv64';
 const isDebug = process.features.debug;

test/regression/issue/patch-bounds-check.test.ts

@@ -1,12 +1,6 @@
 import { expect, test } from "bun:test";
-import { bunEnv, bunExe, normalizeBunSnapshot as normalizeBunSnapshot_, tempDirWithFiles } from "harness";
-
-const normalizeBunSnapshot = (str: string) => {
-  str = normalizeBunSnapshot_(str);
-  str = str.replace(/.*Resolved, downloaded and extracted.*\n?/g, "");
-  str = str.replaceAll("fstatat()", "stat()");
-  return str;
-};
+import { bunEnv, bunExe, tempDirWithFiles } from "harness";
+import { normalizeBunSnapshotForPatch as normalizeBunSnapshot } from "../../harness-patch";
 
 test("patch application should handle out-of-bounds line numbers gracefully", async () => {
   const dir = tempDirWithFiles("patch-bounds-test", {