File data source lists names of files only if they start with basename

cgmes/cgmes-conversion/src/test/java/com/powsybl/cgmes/conversion/test/ConversionTester.java

@@ -205,21 +205,22 @@ private void testExportImportCgmes(Network network, ReadOnlyDataSource originalD
 
         Path path = fs.getPath("temp-export-cgmes");
         Files.createDirectories(path);
-        new CgmesExport().export(network, exportParams, new FileDataSource(path, "bar"));
+        String baseName = "bar";
+        new CgmesExport().export(network, exportParams, new FileDataSource(path, baseName));
 
         DataSource ds = new FileDataSource(path, "bar");
         String expected = originalDs.listNames(".*EQ.*").stream().filter(name -> !name.contains("BD")).findFirst().orElseThrow(() -> new CgmesModelException("Should contain EQ profile"));
-        try (OutputStream out = new BufferedOutputStream(ds.newOutputStream(network.getNameOrId() + "_EQ.xml", false));
+        try (OutputStream out = new BufferedOutputStream(ds.newOutputStream(baseName + "_EQ.xml", false));
              InputStream in = originalDs.newInputStream(expected)) {
             ByteStreams.copy(in, out);
         }
         expected = originalDs.listNames(".*TP.*").stream().filter(name -> !name.contains("BD")).findFirst().orElseThrow(() -> new CgmesModelException("Should contain TP profile"));
-        try (OutputStream out = new BufferedOutputStream(ds.newOutputStream(network.getNameOrId() + "_TP.xml", false));
+        try (OutputStream out = new BufferedOutputStream(ds.newOutputStream(baseName + "_TP.xml", false));
              InputStream in = originalDs.newInputStream(expected)) {
             ByteStreams.copy(in, out);
         }
         for (String boundary : originalDs.listNames(".*BD.*")) {
-            try (OutputStream out = new BufferedOutputStream(ds.newOutputStream(boundary, false));
+            try (OutputStream out = new BufferedOutputStream(ds.newOutputStream(baseName + boundary, false));
                  InputStream in = originalDs.newInputStream(boundary)) {
                 ByteStreams.copy(in, out);
             }

commons/src/main/java/com/powsybl/commons/datasource/FileDataSource.java

@@ -107,6 +107,7 @@ public Set<String> listNames(String regex) throws IOException {
                     .filter(Files::isRegularFile)
                     .map(Path::getFileName)
                     .map(Path::toString)
+                    .filter(name -> name.startsWith(baseName))
                     // Return names after removing the compression extension
                     .map(name -> name.replace(getCompressionExt(),  ""))
                     .filter(s -> p.matcher(s).matches())

commons/src/test/java/com/powsybl/commons/datasource/FileDataSourceTest.java

@@ -6,6 +6,16 @@
  */
 package com.powsybl.commons.datasource;
 
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.Set;
+
+import static org.junit.Assert.*;
+
 /**
  * @author Geoffroy Jamgotchian <geoffroy.jamgotchian at rte-france.com>
  */
@@ -15,4 +25,66 @@ public class FileDataSourceTest extends AbstractDataSourceTest {
     protected DataSource createDataSource() {
         return new FileDataSource(testDir, getBaseName());
     }
+
+    @Test
+    public void listNamesTest() throws IOException {
+        // Create a couple of files in the test folder
+        // One using the basename
+        String validFilename = getBaseName() + ".txt";
+        try (OutputStream os = Files.newOutputStream(testDir.resolve(validFilename))) {
+            os.write("basename_line".getBytes(StandardCharsets.UTF_8));
+        }
+        // Other that has a different name
+        String otherFilename = "other.txt";
+        try (OutputStream os = Files.newOutputStream(testDir.resolve(otherFilename))) {
+            os.write("other_line".getBytes(StandardCharsets.UTF_8));
+        }
+
+        // A file data source created using the complete filename does not return other filenames
+        Set<String> names = new FileDataSource(testDir, getBaseName() + ".txt").listNames(".*");
+        assertEquals(1, names.size());
+        assertTrue(names.contains(validFilename));
+        assertFalse(names.contains(otherFilename));
+
+        // A file data source created using the test folder and the basename sees only the right file
+        names = new FileDataSource(testDir, getBaseName()).listNames(".*");
+        assertEquals(1, names.size());
+        assertTrue(names.contains(validFilename));
+        assertFalse(names.contains(otherFilename));
+    }
+
+    @Test
+    public void createNewFilesTest() throws IOException {
+        DataSource ds = createDataSource();
+
+        // use the data source to write a file that contains basename
+        String suffix = "suffix";
+        String ext = "ext";
+        try (OutputStream os = ds.newOutputStream(suffix, ext, false)) {
+            os.write("line".getBytes(StandardCharsets.UTF_8));
+        }
+
+        // it is allowed to use the data source to write a file that does not contain the basename
+        try (OutputStream os = ds.newOutputStream("dummy.txt", false)) {
+            os.write("dummy_line".getBytes(StandardCharsets.UTF_8));
+        }
+
+        // write another file in the same directory of data source that does not contain the basename
+        // do not use the data source, just write in the same directory
+        try (OutputStream os = Files.newOutputStream(testDir.resolve("dummy2.txt"))) {
+            os.write("dummy2_line".getBytes(StandardCharsets.UTF_8));
+        }
+
+        // check the three files exists when checked through the data source
+        assertTrue(ds.exists(suffix, ext));
+        assertTrue(ds.exists("dummy.txt"));
+        assertTrue(ds.exists("dummy2.txt"));
+
+        // but only the files that contain the basename can be accessed through list names
+        Set<String> names = ds.listNames(".*");
+        assertEquals(1, names.size());
+        assertTrue(names.contains(getBaseName() + suffix + "." + ext));
+        assertFalse(names.contains("dummy.txt"));
+        assertFalse(names.contains("dummy2.txt"));
+    }
 }