diff --git a/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php b/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php
index afa39e532..52589d5dd 100644
--- a/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php
+++ b/tests/Composer/Test/DependencyResolver/PoolBuilderTest.php
@@ -140,6 +140,9 @@ class PoolBuilderTest extends TestCase
         $this->assertSame($expect, $result);
     }
 
+    /**
+     * @return array<string, array<string>>
+     */
     public function getIntegrationTests()
     {
         $fixturesDir = realpath(__DIR__.'/Fixtures/poolbuilder/');
@@ -173,6 +176,11 @@ class PoolBuilderTest extends TestCase
         return $tests;
     }
 
+    /**
+     * @param \SplFileInfo $file
+     * @param string $fixturesDir
+     * @return array<string, string>
+     */
     protected function readTestFile(\SplFileInfo $file, $fixturesDir)
     {
         $tokens = preg_split('#(?:^|\n*)--([A-Z-]+)--\n#', file_get_contents($file->getRealPath()), -1, PREG_SPLIT_DELIM_CAPTURE);
diff --git a/tests/Composer/Test/DependencyResolver/PoolTest.php b/tests/Composer/Test/DependencyResolver/PoolTest.php
index da5385589..350a5cab8 100644
--- a/tests/Composer/Test/DependencyResolver/PoolTest.php
+++ b/tests/Composer/Test/DependencyResolver/PoolTest.php
@@ -57,7 +57,11 @@ class PoolTest extends TestCase
         $this->assertEquals(array(), $pool->whatProvides('foo'));
     }
 
-    protected function createPool(array $packages = array())
+    /**
+     * @param array<\Composer\Package\BasePackage>|null $packages
+     * @return \Composer\DependencyResolver\Pool
+     */
+    protected function createPool($packages = array())
     {
         return new Pool($packages);
     }
diff --git a/tests/Composer/Test/DependencyResolver/SolverTest.php b/tests/Composer/Test/DependencyResolver/SolverTest.php
index 178793b33..539e0e80b 100644
--- a/tests/Composer/Test/DependencyResolver/SolverTest.php
+++ b/tests/Composer/Test/DependencyResolver/SolverTest.php
@@ -1039,12 +1039,18 @@ class SolverTest extends TestCase
         $this->assertTrue($this->solver->testFlagLearnedPositiveLiteral);
     }
 
+    /**
+     * @return void
+     */
     protected function reposComplete()
     {
         $this->repoSet->addRepository($this->repo);
         $this->repoSet->addRepository($this->repoLocked);
     }
 
+    /**
+     * @return void
+     */
     protected function createSolver()
     {
         $io = new NullIO();
@@ -1052,6 +1058,10 @@ class SolverTest extends TestCase
         $this->solver = new Solver($this->policy, $this->pool, $io);
     }
 
+    /**
+     * @param array<array<string, string>> $expected
+     * @return void
+     */
     protected function checkSolverResult(array $expected)
     {
         $this->createSolver();
diff --git a/tests/Composer/Test/DependencyResolver/TransactionTest.php b/tests/Composer/Test/DependencyResolver/TransactionTest.php
index f909fd0b6..76f6beede 100644
--- a/tests/Composer/Test/DependencyResolver/TransactionTest.php
+++ b/tests/Composer/Test/DependencyResolver/TransactionTest.php
@@ -98,6 +98,11 @@ class TransactionTest extends TestCase
         $this->checkTransactionOperations($transaction, $expectedOperations);
     }
 
+    /**
+     * @param \Composer\DependencyResolver\Transaction $transaction
+     * @param array<array<string, string>> $expected
+     * @return void
+     */
     protected function checkTransactionOperations(Transaction $transaction, array $expected)
     {
         $result = array();