[YouTube] Add tests for signature timestamp extraction and signature deobfuscation function extraction and execution

extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/YoutubeSignaturesTest.java

@@ -0,0 +1,53 @@
+package org.schabi.newpipe.extractor.services.youtube;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+import org.junit.jupiter.params.provider.ValueSource;
+import org.schabi.newpipe.downloader.DownloaderTestImpl;
+import org.schabi.newpipe.extractor.NewPipe;
+
+import javax.annotation.Nonnull;
+import java.io.IOException;
+
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+class YoutubeSignaturesTest {
+
+    @BeforeEach
+    void setUp() throws IOException {
+        NewPipe.init(DownloaderTestImpl.getInstance());
+        YoutubeTestsUtils.ensureStateless();
+    }
+
+    @ValueSource(strings = {
+            "QzUGs1qRTEI",
+            ""
+    })
+    @ParameterizedTest
+    void testSignatureTimestampExtraction(@Nonnull final String videoId) throws Exception {
+        final Integer signatureTimestamp =
+                YoutubeJavaScriptPlayerManager.getSignatureTimestamp(videoId);
+        assertTrue(signatureTimestamp > 0, "signatureTimestamp is <= 0");
+    }
+
+    /*
+    The first column of the CSV entries is a video ID
+    The second one of these entries are not real signatures, but as the deobfuscation function
+    manipulates strings, we can use random characters combined as strings to test the extraction
+    and the execution of the function
+     */
+    @CsvSource(value = {
+            "QzUGs1qRTEI,5QjJrWzVcOutYYNyxkDJVkzQDZQxNbbxGi4hRoh2h4PomQMQq9vo2WPHVpHgxRn7qT3WyhRiJa1k1t1DL3lynZtupHmG3wW4qh59faKjtY4UVu",
+            ",7vIK4hG6NbcIEQP4ZIRjonOzuPHh7wTrEgBdEMYyfE4F5Pq0FiGdv04kptb587c8aToH345ETJ8dMbXnpOmjanP3nzgJ0iNg8oHIm8oeQODPSP"
+    })
+    @ParameterizedTest
+    void testSignatureDeobfuscation(@Nonnull final String videoId,
+                                    @Nonnull final String sampleString) throws Exception {
+        // As the signature deobfuscation changes frequently with player versions, we can only test
+        // that we get a different string than the original one
+        assertNotEquals(sampleString,
+                YoutubeJavaScriptPlayerManager.deobfuscateSignature(videoId, sampleString));
+    }
+}