improve-fetchers (#11715)

* Make getTrustLevel() mandatory

* Remove obsolete `@Override`

* Really remoe TrustLevel

* Fix link

* Fix checkstyle

* Fix tests

src/main/java/org/jabref/logic/importer/FulltextFetcher.java

@@ -30,7 +30,5 @@ public interface FulltextFetcher {
      *
      * @return The trust level of the fetcher, the higher the better
      */
-    default TrustLevel getTrustLevel() {
-        return TrustLevel.UNKNOWN;
-    }
+    TrustLevel getTrustLevel();
 }

src/main/java/org/jabref/logic/importer/FulltextFetchers.java

@@ -14,7 +14,6 @@
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Predicate;
-import java.util.stream.Collectors;
 
 import org.jabref.logic.net.URLDownload;
 import org.jabref.logic.util.HeadlessExecutorService;
@@ -113,6 +112,6 @@ private Callable<Optional<FetcherResult>> getCallable(BibEntry entry, FulltextFe
     private List<Callable<Optional<FetcherResult>>> getCallables(BibEntry entry, Set<FulltextFetcher> fetchers) {
         return fetchers.stream()
                        .map(f -> getCallable(entry, f))
-                       .collect(Collectors.toList());
+                       .toList();
     }
 }

src/main/java/org/jabref/logic/importer/fetcher/CiteSeer.java

@@ -113,4 +113,9 @@ public Optional<URL> findFullText(BibEntry entry) throws IOException, FetcherExc
 
         return Optional.empty();
     }
+
+    @Override
+    public TrustLevel getTrustLevel() {
+        return TrustLevel.META_SEARCH;
+    }
 }

src/main/java/org/jabref/logic/importer/fetcher/JstorFetcher.java

@@ -132,9 +132,4 @@ public Optional<URL> findFullText(BibEntry entry) throws FetcherException, IOExc
     public TrustLevel getTrustLevel() {
         return TrustLevel.META_SEARCH;
     }
-
-    @Override
-    public void doPostCleanup(BibEntry entry) {
-        // do nothing
-    }
 }

src/main/java/org/jabref/logic/importer/fetcher/TrustLevel.java

@@ -1,7 +1,7 @@
 package org.jabref.logic.importer.fetcher;
 
 /**
- * Discussion on the trust levels is available at our <a href="https://devdocs.jabref.org/advanced-reading/fetchers">documentation on fetchers</a>.
+ * Discussion on the trust levels is available at our <a href="https://devdocs.jabref.org/code-howtos/fetchers.html#fulltext-fetchers">documentation on fulltext fetchers</a>.
  */
 public enum TrustLevel {
     SOURCE(3),

src/test/java/org/jabref/logic/importer/FulltextFetchersTest.java

@@ -20,36 +20,47 @@
 @FetcherTest
 class FulltextFetchersTest {
 
-    private BibEntry entry = new BibEntry();
+    /**
+     * Required for testing the FulltextFetchers class.
+     * That code is not put to the FulltextFetcher class itself, because subclasses of FulltextFetcher should implement the getTrustLevel method.
+     */
+    private interface FulltextFetcherWithTrustLevel extends FulltextFetcher {
+        default TrustLevel getTrustLevel() {
+            return TrustLevel.UNKNOWN;
+        }
+    }
 
     @Test
     void acceptPdfUrls() throws MalformedURLException {
         URL pdfUrl = new URL("http://docs.oasis-open.org/wsbpel/2.0/OS/wsbpel-v2.0-OS.pdf");
-        FulltextFetcher finder = e -> Optional.of(pdfUrl);
+        FulltextFetcherWithTrustLevel finder = e -> Optional.of(pdfUrl);
         FulltextFetchers fetcher = new FulltextFetchers(Set.of(finder));
-        assertEquals(Optional.of(pdfUrl), fetcher.findFullTextPDF(entry));
+        assertEquals(Optional.of(pdfUrl), fetcher.findFullTextPDF(new BibEntry()));
     }
 
     @Test
     void rejectNonPdfUrls() throws MalformedURLException {
         URL pdfUrl = new URL("https://github.com/JabRef/jabref/blob/master/README.md");
-        FulltextFetcher finder = e -> Optional.of(pdfUrl);
+        FulltextFetcherWithTrustLevel finder = e -> Optional.of(pdfUrl);
         FulltextFetchers fetcher = new FulltextFetchers(Set.of(finder));
 
-        assertEquals(Optional.empty(), fetcher.findFullTextPDF(entry));
+        assertEquals(Optional.empty(), fetcher.findFullTextPDF(new BibEntry()));
     }
 
     @Test
     void noTrustLevel() throws MalformedURLException {
         URL pdfUrl = new URL("http://docs.oasis-open.org/wsbpel/2.0/OS/wsbpel-v2.0-OS.pdf");
-        FulltextFetcher finder = e -> Optional.of(pdfUrl);
+        FulltextFetcherWithTrustLevel finder = e -> Optional.of(pdfUrl);
         FulltextFetchers fetcher = new FulltextFetchers(Set.of(finder));
 
-        assertEquals(Optional.of(pdfUrl), fetcher.findFullTextPDF(entry));
+        assertEquals(Optional.of(pdfUrl), fetcher.findFullTextPDF(new BibEntry()));
     }
 
     @Test
     void higherTrustLevelWins() throws IOException, FetcherException {
+        // set an (arbitrary) DOI to the test entry to skip side effects inside the "findFullTextPDF" method
+        BibEntry entry = new BibEntry().withField(StandardField.DOI, "10.5220/0007903201120130");
+
         FulltextFetcher finderHigh = mock(FulltextFetcher.class);
         when(finderHigh.getTrustLevel()).thenReturn(TrustLevel.SOURCE);
         final URL highUrl = new URL("http://docs.oasis-open.org/wsbpel/2.0/OS/wsbpel-v2.0-OS.pdf");
@@ -60,11 +71,8 @@ void higherTrustLevelWins() throws IOException, FetcherException {
         final URL lowUrl = new URL("http://docs.oasis-open.org/opencsa/sca-bpel/sca-bpel-1.1-spec-cd-01.pdf");
         when(finderLow.findFullText(entry)).thenReturn(Optional.of(lowUrl));
 
-        FulltextFetchers fetcher = new FulltextFetchers(Set.of(finderLow, finderHigh));
-
-        // set an (arbitrary) DOI to the test entry to skip side effects inside the "findFullTextPDF" method
-        entry.setField(StandardField.DOI, "10.5220/0007903201120130");
+        FulltextFetchers fetchers = new FulltextFetchers(Set.of(finderLow, finderHigh));
 
-        assertEquals(Optional.of(highUrl), fetcher.findFullTextPDF(entry));
+        assertEquals(Optional.of(highUrl), fetchers.findFullTextPDF(entry));
     }
 }

src/test/java/org/jabref/logic/importer/WebFetchersTest.java

@@ -35,7 +35,10 @@
 class WebFetchersTest {
 
     private static final Logger LOGGER = LoggerFactory.getLogger(WebFetchersTest.class);
-    private static final Set<String> IGNORED_INACCESSIBLE_FETCHERS = Set.of("ArXivFetcher$ArXiv");
+
+    private static final Set<String> IGNORED_INACCESSIBLE_FETCHERS = Set.of(
+            "org.jabref.logic.importer.fetcher.ArXivFetcher$ArXiv",
+            "org.jabref.logic.importer.FulltextFetchersTest$FulltextFetcherWithTrustLevel");
 
     private ImportFormatPreferences importFormatPreferences;
     private ImporterPreferences importerPreferences;
@@ -49,7 +52,7 @@ void setUp() {
 
     private Set<Class<?>> getIgnoredInaccessibleClasses() {
         return IGNORED_INACCESSIBLE_FETCHERS.stream()
-                     .map(className -> "org.jabref.logic.importer.fetcher." + className)
+                     .map(className -> "" + className)
                      .map(classPath -> {
                          try {
                              return Class.forName(classPath);