diff --git a/tests/Unit/Plugins/Tia/ContentHash.php b/tests/Unit/Plugins/Tia/ContentHash.php
new file mode 100644
index 00000000..d1b2087b
--- /dev/null
+++ b/tests/Unit/Plugins/Tia/ContentHash.php
@@ -0,0 +1,261 @@
+<?php
+
+use Pest\Plugins\Tia\ContentHash;
+
+describe('of()', function () {
+    it('returns false when file does not exist', function () {
+        expect(ContentHash::of('/path/that/does/not/exist.php'))->toBeFalse();
+    });
+
+    it('hashes an existing file', function () {
+        $path = tempnam(sys_get_temp_dir(), 'pest_').'.php';
+        file_put_contents($path, "<?php echo 'hi';");
+
+        try {
+            expect(ContentHash::of($path))->toBeString()->not->toBeEmpty();
+        } finally {
+            @unlink($path);
+        }
+    });
+});
+
+describe('PHP files', function () {
+    it('produces the same hash regardless of whitespace differences', function () {
+        $a = ContentHash::ofContent('a.php', "<?php \$foo   =   1;\n\necho   \$foo;");
+        $b = ContentHash::ofContent('a.php', "<?php \$foo=1; echo \$foo;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('ignores single-line comments', function () {
+        $a = ContentHash::ofContent('a.php', "<?php\n// this is a comment\n\$foo = 1;");
+        $b = ContentHash::ofContent('a.php', "<?php\n\$foo = 1;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('ignores hash-style comments', function () {
+        $a = ContentHash::ofContent('a.php', "<?php\n# hash comment\n\$foo = 1;");
+        $b = ContentHash::ofContent('a.php', "<?php\n\$foo = 1;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('ignores multi-line comments', function () {
+        $a = ContentHash::ofContent('a.php', "<?php\n/* a multi\n line comment */\n\$foo = 1;");
+        $b = ContentHash::ofContent('a.php', "<?php\n\$foo = 1;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('ignores doc comments', function () {
+        $a = ContentHash::ofContent('a.php', "<?php\n/**\n * @return int\n */\nfunction foo() { return 1; }");
+        $b = ContentHash::ofContent('a.php', "<?php\nfunction foo() { return 1; }");
+
+        expect($a)->toBe($b);
+    });
+
+    it('detects code changes', function () {
+        $a = ContentHash::ofContent('a.php', "<?php \$foo = 1;");
+        $b = ContentHash::ofContent('a.php', "<?php \$foo = 2;");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('preserves whitespace inside string literals', function () {
+        $a = ContentHash::ofContent('a.php', "<?php \$foo = 'hello world';");
+        $b = ContentHash::ofContent('a.php', "<?php \$foo = 'helloworld';");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('treats variable renames as a change', function () {
+        $a = ContentHash::ofContent('a.php', "<?php \$foo = 1;");
+        $b = ContentHash::ofContent('a.php', "<?php \$bar = 1;");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('falls back to a raw hash for unparseable PHP', function () {
+        $hash = ContentHash::ofContent('a.php', 'not valid php at all');
+
+        expect($hash)->toBeString()->not->toBeEmpty();
+    });
+
+    it('is case-insensitive on the file extension', function () {
+        $a = ContentHash::ofContent('a.PHP', "<?php\n// comment\n\$foo = 1;");
+        $b = ContentHash::ofContent('a.php', "<?php\n\$foo = 1;");
+
+        expect($a)->toBe($b);
+    });
+});
+
+describe('Blade files', function () {
+    it('strips blade comments', function () {
+        $a = ContentHash::ofContent('a.blade.php', "<div>{{-- a comment --}}Hello</div>");
+        $b = ContentHash::ofContent('a.blade.php', "<div>Hello</div>");
+
+        expect($a)->toBe($b);
+    });
+
+    it('strips multi-line blade comments', function () {
+        $a = ContentHash::ofContent('a.blade.php', "<div>\n{{--\n multi\n line\n--}}\nHello\n</div>");
+        $b = ContentHash::ofContent('a.blade.php', "<div> Hello </div>");
+
+        expect($a)->toBe($b);
+    });
+
+    it('collapses whitespace', function () {
+        $a = ContentHash::ofContent('a.blade.php', "<div>\n  Hello\n  World\n</div>");
+        $b = ContentHash::ofContent('a.blade.php', "<div> Hello World </div>");
+
+        expect($a)->toBe($b);
+    });
+
+    it('detects content changes', function () {
+        $a = ContentHash::ofContent('a.blade.php', "<div>Hello</div>");
+        $b = ContentHash::ofContent('a.blade.php', "<div>Goodbye</div>");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('keeps blade directives intact', function () {
+        $a = ContentHash::ofContent('a.blade.php', "@if(\$user)Hi @endif");
+        $b = ContentHash::ofContent('a.blade.php', "@if(\$user)Bye @endif");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('does not use the PHP tokenizer for blade files', function () {
+        $a = ContentHash::ofContent('a.blade.php', "<?php // not stripped ?> hello");
+        $b = ContentHash::ofContent('a.blade.php', "<?php ?> hello");
+
+        expect($a)->not->toBe($b);
+    });
+});
+
+describe('JavaScript-like files', function () {
+    it('strips line comments', function () {
+        $a = ContentHash::ofContent('a.js', "// a comment\nconst foo = 1;");
+        $b = ContentHash::ofContent('a.js', "const foo = 1;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('strips block comments on their own lines', function () {
+        $a = ContentHash::ofContent('a.js', "/* block */\nconst foo = 1;");
+        $b = ContentHash::ofContent('a.js', "const foo = 1;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('collapses whitespace', function () {
+        $a = ContentHash::ofContent('a.js', "const  foo  =  1;\n\nconst bar = 2;");
+        $b = ContentHash::ofContent('a.js', "const foo = 1; const bar = 2;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('detects code changes', function () {
+        $a = ContentHash::ofContent('a.js', "const foo = 1;");
+        $b = ContentHash::ofContent('a.js', "const foo = 2;");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('does not strip inline trailing comments', function () {
+        $a = ContentHash::ofContent('a.js', "const foo = 1; // inline");
+        $b = ContentHash::ofContent('a.js', "const foo = 1;");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('applies the same rules to .ts files', function () {
+        $a = ContentHash::ofContent('a.ts', "// comment\nconst foo: number = 1;");
+        $b = ContentHash::ofContent('a.ts', "const foo: number = 1;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('applies the same rules to .tsx files', function () {
+        $a = ContentHash::ofContent('a.tsx', "// comment\nconst Foo = () => <div/>;");
+        $b = ContentHash::ofContent('a.tsx', "const Foo = () => <div/>;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('applies the same rules to .jsx files', function () {
+        $a = ContentHash::ofContent('a.jsx', "// comment\nconst Foo = () => <div/>;");
+        $b = ContentHash::ofContent('a.jsx', "const Foo = () => <div/>;");
+
+        expect($a)->toBe($b);
+    });
+
+    it('applies the same rules to .vue files', function () {
+        $a = ContentHash::ofContent('a.vue', "<script>\n// comment\nexport default {}\n</script>");
+        $b = ContentHash::ofContent('a.vue', "<script> export default {} </script>");
+
+        expect($a)->toBe($b);
+    });
+
+    it('applies the same rules to .svelte files', function () {
+        $a = ContentHash::ofContent('a.svelte', "<script>\n// comment\nlet foo = 1;\n</script>");
+        $b = ContentHash::ofContent('a.svelte', "<script> let foo = 1; </script>");
+
+        expect($a)->toBe($b);
+    });
+
+    it('applies the same rules to .mjs, .cjs, and .mts files', function () {
+        foreach (['mjs', 'cjs', 'mts'] as $ext) {
+            $a = ContentHash::ofContent("a.$ext", "// comment\nexport const foo = 1;");
+            $b = ContentHash::ofContent("a.$ext", "export const foo = 1;");
+
+            expect($a)->toBe($b);
+        }
+    });
+});
+
+describe('unknown extensions', function () {
+    it('hashes the raw content for unknown extensions', function () {
+        $a = ContentHash::ofContent('a.txt', "hello world");
+        $b = ContentHash::ofContent('a.txt', "hello world");
+
+        expect($a)->toBe($b);
+    });
+
+    it('does not normalise whitespace for unknown extensions', function () {
+        $a = ContentHash::ofContent('a.txt', "hello  world");
+        $b = ContentHash::ofContent('a.txt', "hello world");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('does not strip comments for unknown extensions', function () {
+        $a = ContentHash::ofContent('a.txt', "// not a comment here\nhello");
+        $b = ContentHash::ofContent('a.txt', "hello");
+
+        expect($a)->not->toBe($b);
+    });
+
+    it('hashes files with no extension as raw content', function () {
+        $a = ContentHash::ofContent('Makefile', "all:\n\techo hi");
+        $b = ContentHash::ofContent('Makefile', "all:\n\techo hi");
+
+        expect($a)->toBe($b);
+    });
+});
+
+describe('output format', function () {
+    it('returns a 32-character hex xxh128 hash', function () {
+        $hash = ContentHash::ofContent('a.php', '<?php $foo = 1;');
+
+        expect($hash)->toMatch('/^[a-f0-9]{32}$/');
+    });
+
+    it('returns a stable hash for empty content', function () {
+        $a = ContentHash::ofContent('a.php', '');
+        $b = ContentHash::ofContent('a.php', '');
+
+        expect($a)->toBe($b);
+    });
+});