fix(test): portable MkdirAll-failure path for Windows (#101)

* fix(test): portable MkdirAll-failure path for Windows

TestWriteIDExclusive_mkdirFailure passed `/dev/null/impossible/path/id`
expecting MkdirAll to fail because `/dev/null` is a char-device file.
That's only true on POSIX — on Windows there is no `/dev/null`, so
MkdirAll happily creates `C:\dev\null\impossible\path\` and the test
failed.

Switch to a portable trick: create a regular file in t.TempDir(), then
pass `<that-file>/impossible/id` as the path. Every OS treats a
regular file as a non-directory and refuses to descend into it
(POSIX: ENOTDIR, Windows: ERROR_DIRECTORY). MkdirAll returns
non-nil either way, which is the contract the test pins.

No production code change — the writeIDExclusive function itself
behaves correctly on both platforms; only the test setup was
platform-specific.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

* chore: bump version to 0.17.3 for Windows test hotfix

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: 8bitAlex

site/docs/whats-new.mdx

@@ -9,6 +9,12 @@ description: Feature-by-feature release notes for Raid.
 
 User-visible changes per release, latest first. For full commit history see the [GitHub releases page](https://github.com/8bitalex/raid/releases).
 
+## 0.17.3 — upcoming
+
+Test-only hotfix. No behavior change to the shipped binary.
+
+**`TestWriteIDExclusive_mkdirFailure` now passes on Windows.** The test pinned `writeIDExclusive`'s "MkdirAll fails → error returned" contract by passing `/dev/null/impossible/path/id` — a path that only forces `MkdirAll` to fail on POSIX, where `/dev/null` is a char-device file the kernel refuses to descend into. On Windows there is no `/dev/null`, so `MkdirAll` happily created `C:\dev\null\impossible\path\` and the test failed with no returned error. Replaced with a portable file-as-parent-dir trick (write a regular file, then pass a path that treats it as a directory component) which fails `MkdirAll` on both POSIX (ENOTDIR) and Windows (ERROR_DIRECTORY).
+
 ## 0.17.2 — upcoming
 
 Eighteen High and Medium pre-v1.0 review fixes. No new features; behavior changes are surgical and called out individually below.

src/internal/telemetry/telemetry_test.go

@@ -1064,9 +1064,24 @@ func TestPurgeID_alreadyAbsent(t *testing.T) {
 
 func TestWriteIDExclusive_mkdirFailure(t *testing.T) {
 	setupTestEnv(t)
-	_, err := writeIDExclusive("/dev/null/impossible/path/id", "test-id")
+	// Force MkdirAll to fail in a portable way: create a regular file
+	// and pass a path that treats it as a directory component. On
+	// POSIX this yields ENOTDIR; on Windows it yields ERROR_DIRECTORY
+	// / "the directory name is invalid". Either way MkdirAll returns
+	// non-nil, which is the contract the test pins.
+	//
+	// The previous version passed `/dev/null/impossible/path/id`,
+	// which only fails on POSIX (where /dev/null is a char-device
+	// file). On Windows there is no /dev/null and MkdirAll happily
+	// creates the chain under the current drive, so the test failed.
+	dir := t.TempDir()
+	blocker := filepath.Join(dir, "blocker")
+	if err := os.WriteFile(blocker, []byte("x"), 0600); err != nil {
+		t.Fatalf("setup blocker file: %v", err)
+	}
+	_, err := writeIDExclusive(filepath.Join(blocker, "impossible", "id"), "test-id")
 	if err == nil {
-		t.Fatal("writeIDExclusive() with impossible path should error")
+		t.Fatal("writeIDExclusive() with file-as-parent-dir path should error")
 	}
 }
 

src/resources/app.properties

@@ -1,2 +1,2 @@
-version=0.17.2
+version=0.17.3
 environment=development