Refactors testUnderscore

Renames `testUnderscore` to `testValidatorHandlesUnderscoresInDomainsCorrectly()`,
and has it use a data provider with individual inputs and assertions.

Author: weierophinney

test/HostnameTest.php

@@ -119,28 +119,58 @@ public function testDashes()
         }
     }
 
+    /**
+     * @return iterable
+     */
+    public function domainsWithUnderscores()
+    {
+        yield 'subdomain with leading underscore' => [
+            '_subdomain.domain.com',
+            'assertTrue',
+        ];
+
+        yield 'subdomain with trailing underscore' => [
+            'subdomain_.domain.com',
+            'assertTrue',
+        ];
+
+        yield 'subdomain with single underscore' => [
+            'sub_domain.domain.com',
+            'assertTrue',
+        ];
+
+        yield 'subdomain with double underscore' => [
+            'sub__domain.domain.com',
+            'assertTrue',
+        ];
+
+        yield 'root domain with leading underscore' => [
+            '_domain.com',
+            'assertFalse',
+        ];
+
+        yield 'root domain with trailing underscore' => [
+            'domain_.com',
+            'assertFalse',
+        ];
+
+        yield 'root domain with underscore' => [
+            'do_main.com',
+            'assertFalse',
+        ];
+    }
+
     /**
      * Ensure the underscore character tests work as expected
      *
+     * @dataProvider domainsWithUnderscores
+     * @param string $input
+     * @param string $assertion
      */
-    public function testUnderscores()
+    public function testValidatorHandlesUnderscoresInDomainsCorrectly($input, $assertion)
     {
-        $valuesExpected = [
-            [Hostname::ALLOW_DNS, true, [
-                '_subdomain.domain.com', 'subdomain_.domain.com', 'sub_domain.domain.com', 'sub__domain.domain.com'
-            ]],
-            [Hostname::ALLOW_DNS, false, ['_domain.com', 'domain_.com', 'do_main.com']]
-        ];
-        foreach ($valuesExpected as $element) {
-            $validator = new Hostname($element[0]);
-            foreach ($element[2] as $input) {
-                $this->assertEquals(
-                    $element[1],
-                    $validator->isValid($input),
-                    implode("\n", $validator->getMessages()) . $input
-                );
-            }
-        }
+        $validator = new Hostname(Hostname::ALLOW_DNS);
+        $this->$assertion($validator->isValid($input), implode("\n", $validator->getMessages()));
     }
 
     /**