test: fix test failing on MacOS now we don't do home expansion

Author: ashleyhindle

tests/Unit/Install/HerdTest.php

@@ -77,17 +77,17 @@ function getHerdTestTempDir(): string
     expect($herd->mcpPath())->toBe($expected);
 })->onlyOnWindows();
 
-test('isMcpAvailable returns false when MCP file is missing', function () {
+test('isMcpAvailable returns false when MCP file is missing from home', function () {
     $testHome = getHerdTestTempDir().'/home';
     mkdir($testHome, 0755, true);
     $_SERVER['HOME'] = $testHome;
 
     $herd = new Herd;
 
     expect($herd->isMcpAvailable())->toBeFalse();
-});
+})->onlyOnWindows();
 
-test('isMcpAvailable returns true when MCP file exists', function () {
+test('isMcpAvailable returns true when MCP file exists in home', function () {
     $testHome = getHerdTestTempDir().'/home';
     mkdir($testHome, 0755, true);
     $_SERVER['HOME'] = $testHome;