diff --git a/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java b/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java
index 4948bf1bde36..b166528085f9 100644
--- a/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java
+++ b/platform/testFramework/src/com/intellij/testFramework/UsefulTestCase.java
@@ -31,6 +31,8 @@ import com.intellij.testFramework.exceptionCases.AbstractExceptionCase;
 import com.intellij.testFramework.fixtures.IdeaTestExecutionPolicy;
 import com.intellij.util.*;
 import com.intellij.util.containers.ContainerUtil;
+import com.intellij.util.containers.PeekableIterator;
+import com.intellij.util.containers.PeekableIteratorWrapper;
 import com.intellij.util.containers.hash.HashMap;
 import com.intellij.util.lang.CompoundRuntimeException;
 import com.intellij.util.ui.UIUtil;
@@ -43,6 +45,7 @@ import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.junit.Assert;
+import org.junit.ComparisonFailure;
 
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -559,9 +562,20 @@ public abstract class UsefulTestCase extends TestCase {
   }
 
   public static <T> void assertContainsOrdered(@NotNull Collection<? extends T> collection, @NotNull Collection<? extends T> expected) {
-    ArrayList<T> copy = new ArrayList<>(collection);
-    copy.retainAll(expected);
-    assertOrderedEquals(toString(collection), copy, expected);
+    PeekableIterator<T> expectedIt = new PeekableIteratorWrapper<>(expected.iterator());
+    PeekableIterator<T> actualIt = new PeekableIteratorWrapper<>(collection.iterator());
+
+    while (actualIt.hasNext() && expectedIt.hasNext()) {
+      T expectedElem = expectedIt.peek();
+      T actualElem = actualIt.peek();
+      if (expectedElem.equals(actualElem)) {
+        expectedIt.next();
+      }
+      actualIt.next();
+    }
+    if (expectedIt.hasNext()) {
+      throw new ComparisonFailure("", toString(expected), toString(collection));
+    }
   }
 
   @SafeVarargs
diff --git a/plugins/git4idea/tests/git4idea/ignore/GitIgnoredFileTest.kt b/plugins/git4idea/tests/git4idea/ignore/GitIgnoredFileTest.kt
index 95dc58c65e08..2174fe6a9f31 100644
--- a/plugins/git4idea/tests/git4idea/ignore/GitIgnoredFileTest.kt
+++ b/plugins/git4idea/tests/git4idea/ignore/GitIgnoredFileTest.kt
@@ -4,12 +4,10 @@ package git4idea.ignore
 import com.intellij.openapi.command.WriteCommandAction
 import com.intellij.openapi.vfs.VirtualFile
 import com.intellij.openapi.vfs.encoding.EncodingProjectManager
-import com.intellij.util.containers.PeekableIteratorWrapper
 import git4idea.GitUtil
 import git4idea.repo.GitRepositoryFiles.GITIGNORE
 import git4idea.test.GitPlatformTest
 import git4idea.test.createRepository
-import org.junit.Assert
 import java.io.File
 
 const val OUT = "out"
@@ -60,32 +58,7 @@ class GitIgnoredFileTest : GitPlatformTest() {
     val generatedGitIgnoreContent = gitIgnoreFile.readText(projectCharset)
     assertFalse("Generated ignore file is empty", generatedGitIgnoreContent.isBlank())
     assertFalse("Generated ignore file content should be system-independent", generatedGitIgnoreContent.contains('\\'))
-    assertIncludesAllOrdered(generatedGitIgnoreContent.lines(), gitIgnoreExpectedContentList)
-  }
-
-  private fun assertIncludesAllOrdered(actualList: List<String>, expectedList: List<String>) {
-    val expectedIt = PeekableIteratorWrapper(expectedList.iterator())
-    val actualIt = PeekableIteratorWrapper(actualList.iterator())
-
-    while (actualIt.hasNext() && expectedIt.hasNext()) {
-      val expected = expectedIt.peek()
-      val actual = actualIt.peek()
-      if (expected == actual) {
-        expectedIt.next()
-        actualIt.next()
-      }
-      else {
-        actualIt.next()
-      }
-    }
-
-    if(expectedIt.hasNext()){
-      Assert.fail("""
-         Expected: $expectedList
-         Actual: $actualList
-         Not included in the same order.
-      """.trimIndent())
-    }
+    assertContainsOrdered(generatedGitIgnoreContent.lines(), gitIgnoreExpectedContentList)
   }
 
   private fun VirtualFile.findOrCreateDir(dirName: String) = this.findChild(dirName) ?: createChildDirectory(this, dirName)