add more test coverage

Author: staabm

tests/PHPStan/Analyser/data/non-empty-string-file-functions.php

@@ -12,7 +12,9 @@ class Foo
 	 * @param numeric-string $numericString
 	 */
 	public function strTypes($nonES, $nonFalsyString, $numericString) {
-		if (is_dir($nonES)) {
+		if (dir($nonES)) {
+			assertType('non-empty-string', $nonES);
+		} else {
 			assertType('non-empty-string', $nonES);
 		}
 		assertType('non-empty-string', $nonES);
@@ -32,6 +34,8 @@ public function fileNonEmptyStrings(string $s): void
 	{
 		if (dir($s)) {
 			assertType('non-empty-string', $s);
+		} else {
+			assertType('string', $s);
 		}
 		assertType('string', $s);
 

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -1094,4 +1094,11 @@ public function testBug10502(): void
 		]);
 	}
 
+	public function testBug6788(): void
+	{
+		$this->checkAlwaysTrueCheckTypeFunctionCall = true;
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-6788.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Comparison/data/bug-6788.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Bug6788;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @param non-empty-string $nonES
+ * @param non-falsy-string $nonFalsyString
+ * @param numeric-string $numericString
+ */
+function strTypes($nonES, $nonFalsyString, $numericString) {
+	if (chdir($nonES)) {
+	}
+	if (chdir($nonFalsyString)) {
+	}
+	if (chdir($numericString)) {
+	}
+}