diff --git a/src/AutomataMatcher.php b/src/AutomataMatcher.php
index e9674bd..ccfb4af 100644
--- a/src/AutomataMatcher.php
+++ b/src/AutomataMatcher.php
@@ -161,6 +161,12 @@ private static function parseToken(
      */
     public function match(string $path): ?Rule
     {
+        if (str_starts_with($path, '/') || str_ends_with($path, '/')) {
+            throw new \InvalidArgumentException(
+                "path should be a relative path to a file, thus it cannot start or end with a /"
+            );
+        }
+
         $path = explode('/', $path);
         $index = $this->start->match($path);
         return $index >= 0
diff --git a/src/SimpleMatcher.php b/src/SimpleMatcher.php
index 57d4c55..3abd662 100644
--- a/src/SimpleMatcher.php
+++ b/src/SimpleMatcher.php
@@ -35,6 +35,12 @@ public function __construct(iterable $rules)
      */
     public function match(string $path): ?Rule
     {
+        if (str_starts_with($path, '/') || str_ends_with($path, '/')) {
+            throw new \InvalidArgumentException(
+                "path should be a relative path to a file, thus it cannot start or end with a /"
+            );
+        }
+
         foreach ($this->rules as [$matcher, $rule]) {
             if ($matcher($path)) {
                 return $rule;
diff --git a/tests/AutomataMatcherTest.php b/tests/AutomataMatcherTest.php
index 9a3b807..433ba53 100644
--- a/tests/AutomataMatcherTest.php
+++ b/tests/AutomataMatcherTest.php
@@ -2,8 +2,11 @@
 
 namespace Kellegous\CodeOwners;
 
+use Exception;
 use PHPUnit\Framework\TestCase;
 
+require_once __DIR__ . '/TestProvider.php';
+
 /**
  * @covers AutomataMatcher
  */
@@ -15,49 +18,30 @@ final class AutomataMatcherTest extends TestCase
      */
     public static function getMatchTests(): iterable
     {
-        $tests = include __DIR__ . '/matcher_tests.php';
-        foreach ($tests as $desc => ['lines' => $lines, 'expected' => $expected]) {
-            $matcher = self::matcherWith($lines);
-            foreach ($expected as $path => $line) {
-                yield "{$desc} w/ {$path}" => [
-                    $matcher,
-                    $path,
-                    $line
-                ];
-            }
-        }
+        return TestProvider::forMatchTests(
+            fn(iterable $rules) => AutomataMatcher::build($rules)
+        );
     }
 
     /**
-     * @param string[] $lines
-     * @return AutomataMatcher
+     * @return iterable<array{AutomataMatcher, string, ?int}>
      * @throws ParseException
      */
-    private static function matcherWith(array $lines): AutomataMatcher
+    public static function getExampleTests(): iterable
     {
-        return AutomataMatcher::build(
-            Owners::fromString(
-                implode(PHP_EOL, $lines)
-            )->getRules()
+        return TestProvider::forExampleTests(
+            fn(iterable $rules) => AutomataMatcher::build($rules)
         );
     }
 
     /**
-     * @return iterable<array{AutomataMatcher, string, ?int}>
-     * @throws ParseException
+     * @return iterable<array{AutomataMatcher, string, Exception}>
      */
-    public static function getExampleTests(): iterable
+    public static function getBadInputTests(): iterable
     {
-        $owners = Owners::fromFile(__DIR__ . '/CODEOWNERS.example');
-        $matcher = AutomataMatcher::build($owners->getRules());
-        $tests = include __DIR__ . '/example_tests.php';
-        foreach ($tests as $path => $line) {
-            yield $path => [
-                $matcher,
-                $path,
-                $line
-            ];
-        }
+        return TestProvider::forBadInputTests(
+            fn(iterable $rules) => AutomataMatcher::build($rules)
+        );
     }
 
     /**
@@ -99,4 +83,21 @@ public function testExampleMatch(
             : null;
         self::assertSame($expected_line, $line);
     }
+
+    /**
+     * @param AutomataMatcher $matcher
+     * @param string $path
+     * @param Exception $exception
+     * @return void
+     *
+     * @dataProvider getBadInputTests
+     */
+    public function testBadInput(
+        RuleMatcher $matcher,
+        string $path,
+        Exception $exception
+    ): void {
+        self::expectExceptionObject($exception);
+        $matcher->match($path);
+    }
 }
diff --git a/tests/CODEOWNERS.example b/tests/CODEOWNERS.example
index 10c8981..b1a2865 100644
--- a/tests/CODEOWNERS.example
+++ b/tests/CODEOWNERS.example
@@ -54,4 +54,4 @@ a/**/b @doctocat
 
 # In this example nobody owns the files
 # This line should be ignored by the parser.
-/src
\ No newline at end of file
+/src
diff --git a/tests/PatternTest.php b/tests/PatternTest.php
index 36bc28c..090833e 100644
--- a/tests/PatternTest.php
+++ b/tests/PatternTest.php
@@ -46,4 +46,4 @@ public function testPatternMatch(
             $matcher($path)
         );
     }
-}
\ No newline at end of file
+}
diff --git a/tests/SimpleMatcherTest.php b/tests/SimpleMatcherTest.php
index 6d5c8a6..61e6133 100644
--- a/tests/SimpleMatcherTest.php
+++ b/tests/SimpleMatcherTest.php
@@ -2,8 +2,11 @@
 
 namespace Kellegous\CodeOwners;
 
+use Exception;
 use PHPUnit\Framework\TestCase;
 
+require_once __DIR__ . '/TestProvider.php';
+
 /**
  * @covers SimpleMatcher
  */
@@ -15,49 +18,30 @@ class SimpleMatcherTest extends TestCase
      */
     public static function getMatchTests(): iterable
     {
-        $tests = include __DIR__ . '/matcher_tests.php';
-        foreach ($tests as $desc => ['lines' => $lines, 'expected' => $expected]) {
-            $matcher = self::matcherWith($lines);
-            foreach ($expected as $path => $line) {
-                yield "{$desc} w/ {$path}" => [
-                    $matcher,
-                    $path,
-                    $line
-                ];
-            }
-        }
+        return TestProvider::forMatchTests(
+            fn(iterable $rules) => new SimpleMatcher($rules)
+        );
     }
 
     /**
-     * @param string[] $lines
-     * @return SimpleMatcher
+     * @return iterable<array{SimpleMatcher, string, ?int}>
      * @throws ParseException
      */
-    private static function matcherWith(array $lines): SimpleMatcher
+    public static function getExampleTests(): iterable
     {
-        return new SimpleMatcher(
-            Owners::fromString(
-                implode(PHP_EOL, $lines)
-            )->getRules()
+        return TestProvider::forExampleTests(
+            fn(iterable $rules) => new SimpleMatcher($rules)
         );
     }
 
     /**
-     * @return iterable<array{SimpleMatcher, string, ?int}>
-     * @throws ParseException
+     * @return iterable<array{SimpleMatcher, string, Exception}>
      */
-    public static function getExampleTests(): iterable
+    public static function getBadInputTests(): iterable
     {
-        $owners = Owners::fromFile(__DIR__ . '/CODEOWNERS.example');
-        $matcher = new SimpleMatcher($owners->getRules());
-        $tests = include __DIR__ . '/example_tests.php';
-        foreach ($tests as $path => $line) {
-            yield $path => [
-                $matcher,
-                $path,
-                $line
-            ];
-        }
+        return TestProvider::forBadInputTests(
+            fn(iterable $rules) => new SimpleMatcher($rules)
+        );
     }
 
     /**
@@ -99,4 +83,21 @@ public function testExampleMatch(
             : null;
         self::assertSame($expected_line, $line);
     }
+
+    /**
+     * @param RuleMatcher $matcher
+     * @param string $path
+     * @param Exception $exception
+     * @return void
+     *
+     * @dataProvider getBadInputTests
+     */
+    public function testBadInput(
+        RuleMatcher $matcher,
+        string $path,
+        Exception $exception
+    ): void {
+        self::expectExceptionObject($exception);
+        $matcher->match($path);
+    }
 }
\ No newline at end of file
diff --git a/tests/TestProvider.php b/tests/TestProvider.php
new file mode 100644
index 0000000..1788112
--- /dev/null
+++ b/tests/TestProvider.php
@@ -0,0 +1,91 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Kellegous\CodeOwners;
+
+use Closure;
+use Exception;
+use InvalidArgumentException;
+
+/**
+ * Provides a common set of tests for all RuleMatchers.
+ */
+final class TestProvider
+{
+
+    private function __construct()
+    {
+    }
+
+    /**
+     * @template T extends RulMatcher
+     * @param Closure(iterable<Rule>):T $create_matcher
+     * @return iterable<array{T, string, ?int}>
+     * @throws ParseException
+     */
+    public static function forMatchTests(
+        Closure $create_matcher
+    ): iterable {
+        $tests = include __DIR__ . '/matcher_tests.php';
+        foreach ($tests as $desc => ['lines' => $lines, 'expected' => $expected]) {
+            $rules = Owners::fromString(
+                implode(PHP_EOL, $lines)
+            )->getRules();
+            $matcher = $create_matcher($rules);
+            foreach ($expected as $path => $line) {
+                yield "{$desc} w/ {$path}" => [
+                    $matcher,
+                    $path,
+                    $line
+                ];
+            }
+        }
+    }
+
+    /**
+     * @template T extends RuleMatcher
+     * @param Closure(iterable<Rule>):T $create_matcher
+     * @return iterable<array{T, string, ?int}>
+     * @throws ParseException
+     */
+    public static function forExampleTests(
+        Closure $create_matcher
+    ): iterable {
+        $owners = Owners::fromFile(__DIR__ . '/CODEOWNERS.example');
+        $matcher = $create_matcher($owners->getRules());
+        $tests = include __DIR__ . '/example_tests.php';
+        foreach ($tests as $path => $line) {
+            yield $path => [
+                $matcher,
+                $path,
+                $line
+            ];
+        }
+    }
+
+    /**
+     * @template T extends RuleMatcher
+     * @param Closure(iterable<Rule>):T $create_matcher
+     * @return iterable<array{T, string, Exception}>
+     */
+    public static function forBadInputTests(
+        Closure $create_matcher
+    ): iterable {
+        $matcher = $create_matcher([]);
+        yield 'leading /' => [
+            $matcher,
+            '/foo/bar',
+            new InvalidArgumentException(
+                "path should be a relative path to a file, thus it cannot start or end with a /"
+            )
+        ];
+        yield 'trailing /' => [
+            $matcher,
+            'foo/bar/',
+            new InvalidArgumentException(
+                "path should be a relative path to a file, thus it cannot start or end with a /"
+            )
+        ];
+    }
+}
diff --git a/tests/matcher_tests.php b/tests/matcher_tests.php
index 45c171d..f44c799 100644
--- a/tests/matcher_tests.php
+++ b/tests/matcher_tests.php
@@ -89,8 +89,8 @@
         'lines' => ['/*a/'],
         'expected' => [
             '1a' => null,
-            '2a/b/' => 1,
-            '2a/c/d/' => 1,
+            '2a/b' => 1,
+            '2a/c/d' => 1,
         ]
     ],
     '/a*/' => [
@@ -154,5 +154,4 @@
             'b/d/e' => null,
         ]
     ],
-
-];
\ No newline at end of file
+];