test finding files

untitled/src/main/java/DirConverter.java

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+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+
+public class DirConverter {
+    public static void convertSpecifiedFiles(String dirFullPath, String extension) throws IOException {
+
+    }
+
+    public static ArrayList<String> listFileForFolder(File folder, String extension) {
+        ArrayList<String> filenames = new ArrayList<>();
+        String filename;
+
+        File[] files = folder.listFiles();
+        if (files != null) {
+            for (File file : files) {
+                filename = file.getName();
+                if(filename.endsWith(extension))
+                    filenames.add(file.getName());
+            }
+        }
+
+        return filenames;
+    }
+}

untitled/src/test/java/DirConverterTest.java

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+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.*;
+public class DirConverterTest {
+
+    @Test
+    void testFindingFiles() {
+        File dirPath  = new File("H:\\Lucja\\itaz\\konwersja-liter\\dir\\");
+        ArrayList<String> filenames = new ArrayList<>(Arrays.asList("file.txt", "file_special_characters.txt", "file_to_write.txt"));
+        assertEquals(filenames, DirConverter.listFileForFolder(dirPath, ".txt"));
+    }
+}