diff --git a/tests/Composer/Test/Package/Archiver/ArchivableFilesFinderTest.php b/tests/Composer/Test/Package/Archiver/ArchivableFilesFinderTest.php
index 4742572ea..90db564fa 100644
--- a/tests/Composer/Test/Package/Archiver/ArchivableFilesFinderTest.php
+++ b/tests/Composer/Test/Package/Archiver/ArchivableFilesFinderTest.php
@@ -302,6 +302,9 @@ class ArchivableFilesFinderTest extends TestCase
         ));
     }
 
+    /**
+     * @return string[]
+     */
     protected function getArchivableFiles()
     {
         $files = array();
@@ -316,11 +319,17 @@ class ArchivableFilesFinderTest extends TestCase
         return $files;
     }
 
+    /**
+     * @param string $command
+     *
+     * @return string[]
+     */
     protected function getArchivedFiles($command)
     {
         if (method_exists('Symfony\Component\Process\Process', 'fromShellCommandline')) {
             $process = Process::fromShellCommandline($command, $this->sources);
         } else {
+            // @phpstan-ignore-next-line symfony/process 2.8 accepts a string but not 5.3 which is used only for PHPStan
             $process = new Process($command, $this->sources);
         }
         $process->run();
@@ -339,6 +348,11 @@ class ArchivableFilesFinderTest extends TestCase
         return $files;
     }
 
+    /**
+     * @param string[] $expectedFiles
+     *
+     * @return void
+     */
     protected function assertArchivableFiles($expectedFiles)
     {
         $actualFiles = $this->getArchivableFiles();
diff --git a/tests/Composer/Test/Package/Archiver/ArchiveManagerTest.php b/tests/Composer/Test/Package/Archiver/ArchiveManagerTest.php
index 26dfd9a75..c73091ad1 100644
--- a/tests/Composer/Test/Package/Archiver/ArchiveManagerTest.php
+++ b/tests/Composer/Test/Package/Archiver/ArchiveManagerTest.php
@@ -98,6 +98,12 @@ class ArchiveManagerTest extends ArchiverTest
         unlink($target);
     }
 
+    /**
+     * @param string      $format
+     * @param string|null $fileName
+     *
+     * @return string
+     */
     protected function getTargetName(CompletePackage $package, $format, $fileName = null)
     {
         if (null === $fileName) {
@@ -111,6 +117,8 @@ class ArchiveManagerTest extends ArchiverTest
 
     /**
      * Create local git repository to run tests against!
+     *
+     * @return void
      */
     protected function setupGitRepo()
     {
diff --git a/tests/Composer/Test/Package/Archiver/GitExcludeFilterTest.php b/tests/Composer/Test/Package/Archiver/GitExcludeFilterTest.php
index 650dac6ee..eae607a9b 100644
--- a/tests/Composer/Test/Package/Archiver/GitExcludeFilterTest.php
+++ b/tests/Composer/Test/Package/Archiver/GitExcludeFilterTest.php
@@ -18,7 +18,10 @@ use Composer\Test\TestCase;
 class GitExcludeFilterTest extends TestCase
 {
     /**
-     * @dataProvider patterns
+     * @dataProvider providePatterns
+     *
+     * @param string  $ignore
+     * @param mixed[] $expected
      */
     public function testPatternEscape($ignore, $expected)
     {
@@ -27,7 +30,7 @@ class GitExcludeFilterTest extends TestCase
         $this->assertEquals($expected, $filter->parseGitIgnoreLine($ignore));
     }
 
-    public function patterns()
+    public function providePatterns()
     {
         return array(
             array('app/config/parameters.yml', array('{(?=[^\.])app/(?=[^\.])config/(?=[^\.])parameters\.yml(?=$|/)}', false, false)),
diff --git a/tests/Composer/Test/Package/Archiver/HgExcludeFilterTest.php b/tests/Composer/Test/Package/Archiver/HgExcludeFilterTest.php
index ffcd71b1d..21a0260da 100644
--- a/tests/Composer/Test/Package/Archiver/HgExcludeFilterTest.php
+++ b/tests/Composer/Test/Package/Archiver/HgExcludeFilterTest.php
@@ -18,7 +18,10 @@ use Composer\Test\TestCase;
 class HgExcludeFilterTest extends TestCase
 {
     /**
-     * @dataProvider patterns
+     * @dataProvider providePatterns
+     *
+     * @param string  $ignore
+     * @param mixed[] $expected
      */
     public function testPatternEscape($ignore, $expected)
     {
@@ -27,7 +30,7 @@ class HgExcludeFilterTest extends TestCase
         $this->assertEquals($expected, $filter->patternFromRegex($ignore));
     }
 
-    public function patterns()
+    public function providePatterns()
     {
         return array(
             array('.#', array('#.\\##', false, true)),
diff --git a/tests/Composer/Test/Package/Archiver/PharArchiverTest.php b/tests/Composer/Test/Package/Archiver/PharArchiverTest.php
index 668e101e3..82ed226f3 100644
--- a/tests/Composer/Test/Package/Archiver/PharArchiverTest.php
+++ b/tests/Composer/Test/Package/Archiver/PharArchiverTest.php
@@ -48,6 +48,8 @@ class PharArchiverTest extends ArchiverTest
 
     /**
      * Create a local dummy repository to run tests against!
+     *
+     * @return void
      */
     protected function setupDummyRepo()
     {
@@ -63,13 +65,20 @@ class PharArchiverTest extends ArchiverTest
         chdir($currentWorkDir);
     }
 
+    /**
+     * @param string $path
+     * @param string $content
+     * @param string $currentWorkDir
+     *
+     * @return void
+     */
     protected function writeFile($path, $content, $currentWorkDir)
     {
         if (!file_exists(dirname($path))) {
             mkdir(dirname($path), 0777, true);
         }
 
-        $result = file_put_contents($path, 'a');
+        $result = file_put_contents($path, $content);
         if (false === $result) {
             chdir($currentWorkDir);
             throw new \RuntimeException('Could not save file.');
diff --git a/tests/Composer/Test/Package/Archiver/ZipArchiverTest.php b/tests/Composer/Test/Package/Archiver/ZipArchiverTest.php
index a51ec2a2d..616768c01 100644
--- a/tests/Composer/Test/Package/Archiver/ZipArchiverTest.php
+++ b/tests/Composer/Test/Package/Archiver/ZipArchiverTest.php
@@ -39,6 +39,9 @@ class ZipArchiverTest extends ArchiverTest
         );
     }
 
+    /**
+     * @param array<string, string> $files
+     */
     public function testZipArchive(array $files = array())
     {
         if (!class_exists('ZipArchive')) {
@@ -79,7 +82,10 @@ class ZipArchiverTest extends ArchiverTest
 
     /**
      * Create a local dummy repository to run tests against!
-     * @param array $files
+     *
+     * @param array<string, string|null> $files
+     *
+     * @return void
      */
     protected function setupDummyRepo(array &$files)
     {
@@ -95,6 +101,13 @@ class ZipArchiverTest extends ArchiverTest
         chdir($currentWorkDir);
     }
 
+    /**
+     * @param string $path
+     * @param string $content
+     * @param string $currentWorkDir
+     *
+     * @return void
+     */
     protected function writeFile($path, $content, $currentWorkDir)
     {
         if (!file_exists(dirname($path))) {
diff --git a/tests/Composer/Test/Package/BasePackageTest.php b/tests/Composer/Test/Package/BasePackageTest.php
index 2bbf42593..522722a47 100644
--- a/tests/Composer/Test/Package/BasePackageTest.php
+++ b/tests/Composer/Test/Package/BasePackageTest.php
@@ -44,14 +44,17 @@ class BasePackageTest extends TestCase
     }
 
     /**
-     * @dataProvider formattedVersions
+     * @dataProvider provideFormattedVersions
+     *
+     * @param bool   $truncate
+     * @param string $expected
      */
     public function testFormatVersionForDevPackage(BasePackage $package, $truncate, $expected)
     {
         $this->assertSame($expected, $package->getFullPrettyVersion($truncate));
     }
 
-    public function formattedVersions()
+    public function provideFormattedVersions()
     {
         $data = array(
             array(
diff --git a/tests/Composer/Test/Package/CompletePackageTest.php b/tests/Composer/Test/Package/CompletePackageTest.php
index fe1a783e8..848315a1d 100644
--- a/tests/Composer/Test/Package/CompletePackageTest.php
+++ b/tests/Composer/Test/Package/CompletePackageTest.php
@@ -35,8 +35,10 @@ class CompletePackageTest extends TestCase
     }
 
     /**
-     * Tests memory package naming semantics
      * @dataProvider providerVersioningSchemes
+     *
+     * @param string $name
+     * @param string $version
      */
     public function testPackageHasExpectedNamingSemantics($name, $version)
     {
@@ -47,8 +49,10 @@ class CompletePackageTest extends TestCase
     }
 
     /**
-     * Tests memory package versioning semantics
      * @dataProvider providerVersioningSchemes
+     *
+     * @param string $name
+     * @param string $version
      */
     public function testPackageHasExpectedVersioningSemantics($name, $version)
     {
@@ -60,8 +64,10 @@ class CompletePackageTest extends TestCase
     }
 
     /**
-     * Tests memory package marshalling/serialization semantics
      * @dataProvider providerVersioningSchemes
+     *
+     * @param string $name
+     * @param string $version
      */
     public function testPackageHasExpectedMarshallingSemantics($name, $version)
     {
diff --git a/tests/Composer/Test/Package/Dumper/ArrayDumperTest.php b/tests/Composer/Test/Package/Dumper/ArrayDumperTest.php
index 39f1b0a0b..c4ace9e82 100644
--- a/tests/Composer/Test/Package/Dumper/ArrayDumperTest.php
+++ b/tests/Composer/Test/Package/Dumper/ArrayDumperTest.php
@@ -88,7 +88,12 @@ class ArrayDumperTest extends TestCase
     }
 
     /**
-     * @dataProvider getKeys
+     * @dataProvider provideKeys
+     *
+     * @param string $key
+     * @param mixed  $value
+     * @param string $method
+     * @param mixed  $expectedValue
      */
     public function testKeys($key, $value, $method = null, $expectedValue = null)
     {
@@ -106,7 +111,7 @@ class ArrayDumperTest extends TestCase
         $this->assertSame($expectedValue ?: $value, $config[$key]);
     }
 
-    public function getKeys()
+    public function provideKeys()
     {
         return array(
             array(
@@ -239,6 +244,12 @@ class ArrayDumperTest extends TestCase
         );
     }
 
+    /**
+     * @param string $method
+     * @param mixed  $value
+     *
+     * @return self
+     */
     private function packageExpects($method, $value)
     {
         $this->package
diff --git a/tests/Composer/Test/Package/Loader/ArrayLoaderTest.php b/tests/Composer/Test/Package/Loader/ArrayLoaderTest.php
index 285dd13e4..829fc633e 100644
--- a/tests/Composer/Test/Package/Loader/ArrayLoaderTest.php
+++ b/tests/Composer/Test/Package/Loader/ArrayLoaderTest.php
@@ -134,6 +134,11 @@ class ArrayLoaderTest extends TestCase
         return array(array($validConfig));
     }
 
+    /**
+     * @param array<string, mixed> $config
+     *
+     * @return array<string, mixed>
+     */
     protected function fixConfigWhenLoadConfigIsFalse($config)
     {
         $expectedConfig = $config;
@@ -147,6 +152,8 @@ class ArrayLoaderTest extends TestCase
      * allows require-dev libraries to have transport options included.
      *
      * @dataProvider parseDumpProvider
+     *
+     * @param array<string, mixed> $config
      */
     public function testParseDumpDefaultLoadConfig($config)
     {
@@ -158,6 +165,8 @@ class ArrayLoaderTest extends TestCase
 
     /**
      * @dataProvider parseDumpProvider
+     *
+     * @param array<string, mixed> $config
      */
     public function testParseDumpTrueLoadConfig($config)
     {
@@ -170,6 +179,8 @@ class ArrayLoaderTest extends TestCase
 
     /**
      * @dataProvider parseDumpProvider
+     *
+     * @param array<string, mixed> $config
      */
     public function testParseDumpFalseLoadConfig($config)
     {
@@ -262,7 +273,7 @@ class ArrayLoaderTest extends TestCase
         $this->assertFalse($package->isAbandoned());
     }
 
-    public function pluginApiVersions()
+    public function providePluginApiVersions()
     {
         return array(
             array('1.0'),
@@ -284,7 +295,9 @@ class ArrayLoaderTest extends TestCase
     }
 
     /**
-     * @dataProvider pluginApiVersions
+     * @dataProvider providePluginApiVersions
+     *
+     * @param string $apiVersion
      */
     public function testPluginApiVersionAreKeptAsDeclared($apiVersion)
     {
diff --git a/tests/Composer/Test/Package/Loader/RootPackageLoaderTest.php b/tests/Composer/Test/Package/Loader/RootPackageLoaderTest.php
index 25e74145e..d523debc0 100644
--- a/tests/Composer/Test/Package/Loader/RootPackageLoaderTest.php
+++ b/tests/Composer/Test/Package/Loader/RootPackageLoaderTest.php
@@ -15,6 +15,7 @@ namespace Composer\Test\Package\Loader;
 use Composer\Config;
 use Composer\Package\Loader\RootPackageLoader;
 use Composer\Package\BasePackage;
+use Composer\Package\RootAliasPackage;
 use Composer\Package\RootPackage;
 use Composer\Package\Version\VersionGuesser;
 use Composer\Semver\VersionParser;
@@ -24,6 +25,11 @@ use Prophecy\Argument;
 
 class RootPackageLoaderTest extends TestCase
 {
+    /**
+     * @param array<string, mixed> $data
+     *
+     * @return RootPackage|RootAliasPackage
+     */
     protected function loadPackage($data)
     {
         $manager = $this->getMockBuilder('Composer\\Repository\\RepositoryManager')
diff --git a/tests/Composer/Test/Package/Loader/ValidatingArrayLoaderTest.php b/tests/Composer/Test/Package/Loader/ValidatingArrayLoaderTest.php
index 873d90376..103c34551 100644
--- a/tests/Composer/Test/Package/Loader/ValidatingArrayLoaderTest.php
+++ b/tests/Composer/Test/Package/Loader/ValidatingArrayLoaderTest.php
@@ -20,6 +20,8 @@ class ValidatingArrayLoaderTest extends TestCase
 {
     /**
      * @dataProvider successProvider
+     *
+     * @param array<string, mixed> $config
      */
     public function testLoadSuccess($config)
     {
@@ -206,6 +208,9 @@ class ValidatingArrayLoaderTest extends TestCase
 
     /**
      * @dataProvider errorProvider
+     *
+     * @param array<string, mixed> $config
+     * @param string[]             $expectedErrors
      */
     public function testLoadFailureThrowsException($config, $expectedErrors)
     {
@@ -224,6 +229,9 @@ class ValidatingArrayLoaderTest extends TestCase
 
     /**
      * @dataProvider warningProvider
+     *
+     * @param array<string, mixed> $config
+     * @param string[]             $expectedWarnings
      */
     public function testLoadWarnings($config, $expectedWarnings)
     {
@@ -239,6 +247,10 @@ class ValidatingArrayLoaderTest extends TestCase
 
     /**
      * @dataProvider warningProvider
+     *
+     * @param array<string, mixed> $config
+     * @param string[]             $expectedWarnings
+     * @param bool                 $mustCheck
      */
     public function testLoadSkipsWarningDataWhenIgnoringErrors($config, $expectedWarnings, $mustCheck = true)
     {
diff --git a/tests/Composer/Test/Package/LockerTest.php b/tests/Composer/Test/Package/LockerTest.php
index 29f3e7c2a..bf8957bbe 100644
--- a/tests/Composer/Test/Package/LockerTest.php
+++ b/tests/Composer/Test/Package/LockerTest.php
@@ -255,6 +255,9 @@ class LockerTest extends TestCase
         $this->assertFalse($locker->isFresh());
     }
 
+    /**
+     * @return \PHPUnit\Framework\MockObject\MockObject&\Composer\Json\JsonFile
+     */
     private function createJsonFileMock()
     {
         return $this->getMockBuilder('Composer\Json\JsonFile')
@@ -262,6 +265,9 @@ class LockerTest extends TestCase
             ->getMock();
     }
 
+    /**
+     * @return \PHPUnit\Framework\MockObject\MockObject&\Composer\Installer\InstallationManager
+     */
     private function createInstallationManagerMock()
     {
         $mock = $this->getMockBuilder('Composer\Installer\InstallationManager')
@@ -271,12 +277,20 @@ class LockerTest extends TestCase
         return $mock;
     }
 
+    /**
+     * @return \PHPUnit\Framework\MockObject\MockObject&\Composer\Package\PackageInterface
+     */
     private function createPackageMock()
     {
         return $this->getMockBuilder('Composer\Package\PackageInterface')
             ->getMock();
     }
 
+    /**
+     * @param array<string, string> $customData
+     *
+     * @return false|string
+     */
     private function getJsonContent(array $customData = array())
     {
         $data = array_merge(array(
diff --git a/tests/Composer/Test/Package/RootAliasPackageTest.php b/tests/Composer/Test/Package/RootAliasPackageTest.php
index 00ca7fa05..10f9a179c 100644
--- a/tests/Composer/Test/Package/RootAliasPackageTest.php
+++ b/tests/Composer/Test/Package/RootAliasPackageTest.php
@@ -80,6 +80,9 @@ class RootAliasPackageTest extends TestCase
         $this->assertNotEmpty($alias->getReplaces());
     }
 
+    /**
+     * @return \Prophecy\Prophecy\ObjectProphecy
+     */
     protected function getMockRootPackageInterface()
     {
         $root = $this->prophesize('Composer\\Package\\RootPackage');
diff --git a/tests/Composer/Test/Package/Version/VersionParserTest.php b/tests/Composer/Test/Package/Version/VersionParserTest.php
index 824305a5e..8277a0c0e 100644
--- a/tests/Composer/Test/Package/Version/VersionParserTest.php
+++ b/tests/Composer/Test/Package/Version/VersionParserTest.php
@@ -18,7 +18,10 @@ use Composer\Test\TestCase;
 class VersionParserTest extends TestCase
 {
     /**
-     * @dataProvider getParseNameVersionPairsData
+     * @dataProvider provideParseNameVersionPairsData
+     *
+     * @param string[]                     $pairs
+     * @param array<array<string, string>> $result
      */
     public function testParseNameVersionPairs($pairs, $result)
     {
@@ -27,7 +30,7 @@ class VersionParserTest extends TestCase
         $this->assertSame($result, $versionParser->parseNameVersionPairs($pairs));
     }
 
-    public function getParseNameVersionPairsData()
+    public function provideParseNameVersionPairsData()
     {
         return array(
             array(array('php:^7.0'), array(array('name' => 'php', 'version' => '^7.0'))),
@@ -39,14 +42,18 @@ class VersionParserTest extends TestCase
     }
 
     /**
-     * @dataProvider getIsUpgradeTests
+     * @dataProvider provideIsUpgradeTests
+     *
+     * @param string $from
+     * @param string $to
+     * @param bool   $expected
      */
     public function testIsUpgrade($from, $to, $expected)
     {
         $this->assertSame($expected, VersionParser::isUpgrade($from, $to));
     }
 
-    public function getIsUpgradeTests()
+    public function provideIsUpgradeTests()
     {
         return array(
             array('0.9.0.0', '1.0.0.0', true),
diff --git a/tests/Composer/Test/Package/Version/VersionSelectorTest.php b/tests/Composer/Test/Package/Version/VersionSelectorTest.php
index e02470e6b..863f74243 100644
--- a/tests/Composer/Test/Package/Version/VersionSelectorTest.php
+++ b/tests/Composer/Test/Package/Version/VersionSelectorTest.php
@@ -293,7 +293,12 @@ class VersionSelectorTest extends TestCase
     }
 
     /**
-     * @dataProvider getRecommendedRequireVersionPackages
+     * @dataProvider provideRecommendedRequireVersionPackages
+     *
+     * @param string      $prettyVersion
+     * @param string      $expectedVersion
+     * @param string|null $branchAlias
+     * @param string      $packageName
      */
     public function testFindRecommendedRequireVersion($prettyVersion, $expectedVersion, $branchAlias = null, $packageName = 'foo/bar')
     {
@@ -313,7 +318,7 @@ class VersionSelectorTest extends TestCase
         $this->assertSame($expectedVersion, $recommended);
     }
 
-    public function getRecommendedRequireVersionPackages()
+    public function provideRecommendedRequireVersionPackages()
     {
         return array(
             // real version, expected recommendation, [branch-alias], [pkg name]
@@ -353,6 +358,11 @@ class VersionSelectorTest extends TestCase
         );
     }
 
+    /**
+     * @param string $version
+     *
+     * @return Package
+     */
     private function createPackage($version)
     {
         $parser = new VersionParser();
@@ -360,6 +370,9 @@ class VersionSelectorTest extends TestCase
         return new Package('foo', $parser->normalize($version), $version);
     }
 
+    /**
+     * @return \PHPUnit\Framework\MockObject\MockObject&\Composer\Repository\RepositorySet
+     */
     private function createMockRepositorySet()
     {
         return $this->getMockBuilder('Composer\Repository\RepositorySet')