make the selfLink a best effort if not explicitly true

This stops it from always failing on Windows which is making me so
annoyed when I have to debug stuff on my windows VM.

Fix: #20

src/self-dep.ts

@@ -40,11 +40,8 @@ const linkedAlready = (pkg: Package) => {
 }
 
 export const link = (pkg: Package, where: string) => {
-  if (
-    !pkg.name ||
-    pkg?.tshy?.selfLink === false ||
-    linkedAlready(pkg)
-  ) {
+  const selfLink = pkg?.tshy?.selfLink
+  if (!pkg.name || selfLink === false || linkedAlready(pkg)) {
     return
   }
   const dest = resolve(where, 'node_modules', pkg.name)
@@ -56,7 +53,14 @@ export const link = (pkg: Package, where: string) => {
     symlinkSync(src, dest)
   } catch {
     rimrafSync(dest)
-    symlinkSync(src, dest)
+    let threw = true
+    try {
+      symlinkSync(src, dest)
+      threw = false
+    } finally {
+      // best effort if not set explicitly. suppress error with return.
+      if (threw && selfLink === undefined) return
+    }
   }
 }
 

tap-snapshots/test/self-dep.ts.test.cjs

@@ -58,6 +58,64 @@ Array [
 ]
 `
 
+exports[`test/self-dep.ts > TAP > throw both times, but accept if best-effort > mkdirps 1`] = `
+Array [
+  Array [
+    "{CWD}/some/path/node_modules",
+  ],
+]
+`
+
+exports[`test/self-dep.ts > TAP > throw both times, but accept if best-effort > rimrafs 1`] = `
+Array [
+  Array [
+    "{CWD}/some/path/node_modules/name",
+  ],
+]
+`
+
+exports[`test/self-dep.ts > TAP > throw both times, but accept if best-effort > symlinks 1`] = `
+Array [
+  Array [
+    "../../..",
+    "{CWD}/some/path/node_modules/name",
+  ],
+  Array [
+    "../../..",
+    "{CWD}/some/path/node_modules/name",
+  ],
+]
+`
+
+exports[`test/self-dep.ts > TAP > throw both times, but self-link is required > mkdirps 1`] = `
+Array [
+  Array [
+    "{CWD}/some/path/node_modules",
+  ],
+]
+`
+
+exports[`test/self-dep.ts > TAP > throw both times, but self-link is required > rimrafs 1`] = `
+Array [
+  Array [
+    "{CWD}/some/path/node_modules/name",
+  ],
+]
+`
+
+exports[`test/self-dep.ts > TAP > throw both times, but self-link is required > symlinks 1`] = `
+Array [
+  Array [
+    "../../..",
+    "{CWD}/some/path/node_modules/name",
+  ],
+  Array [
+    "../../..",
+    "{CWD}/some/path/node_modules/name",
+  ],
+]
+`
+
 exports[`test/self-dep.ts > TAP > try one more time if it fails > mkdirps 1`] = `
 Array [
   Array [

test/self-dep.ts

@@ -14,13 +14,15 @@ const mkdirpCalls = t.capture(
 
 import * as FS from 'node:fs'
 let symlinkThrow: Error | undefined = undefined
+let symlinkThrowAgain: Error | undefined = undefined
 const fs = {
   symlinkSync: () => {
     if (symlinkThrow) {
       try {
         throw symlinkThrow
       } finally {
-        symlinkThrow = undefined
+        symlinkThrow = symlinkThrowAgain
+        symlinkThrowAgain = undefined
       }
     }
   },
@@ -75,6 +77,31 @@ t.test('try one more time if it fails', t => {
   t.end()
 })
 
+t.test('throw both times, but accept if best-effort', t => {
+  symlinkThrow = new Error('EPERM')
+  symlinkThrowAgain = new Error('EPERM')
+  link({ name: 'name', version: '1.2.3' }, 'some/path')
+  t.matchSnapshot(symlinkCalls(), 'symlinks')
+  t.matchSnapshot(rimrafCalls(), 'rimrafs')
+  t.matchSnapshot(mkdirpCalls(), 'mkdirps')
+  t.end()
+})
+
+t.test('throw both times, but self-link is required', t => {
+  symlinkThrow = new Error('EPERM')
+  symlinkThrowAgain = new Error('EPERM')
+  t.throws(() =>
+    link(
+      { name: 'name', version: '1.2.3', tshy: { selfLink: true } },
+      'some/path'
+    )
+  )
+  t.matchSnapshot(symlinkCalls(), 'symlinks')
+  t.matchSnapshot(rimrafCalls(), 'rimrafs')
+  t.matchSnapshot(mkdirpCalls(), 'mkdirps')
+  t.end()
+})
+
 t.test('link, but no dirs made', t => {
   link({ name: 'name', version: '1.2.3' }, 'some/path')
   unlink({ name: 'name', version: '1.2.3' }, 'some/path')