Improve n parameter tests

These are currently not working, but the tests said OK because it was not checked what happens if the returned parameter is empty!

-> #1339

Author: litetex

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeJavaScriptPlayerManager.java

@@ -1,5 +1,7 @@
 package org.schabi.newpipe.extractor.services.youtube;
 
+import static org.schabi.newpipe.extractor.utils.Utils.isNullOrEmpty;
+
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.utils.JavaScript;
 
@@ -264,6 +266,10 @@ public static String getUrlWithThrottlingParameterDeobfuscated(
                     cachedThrottlingDeobfuscationFunctionName,
                     obfuscatedThrottlingParameter);
 
+            if (isNullOrEmpty(deobfuscatedThrottlingParameter)) {
+                throw new IllegalStateException("Extracted n-parameter is empty");
+            }
+
             CACHED_THROTTLING_PARAMETERS.put(
                     obfuscatedThrottlingParameter, deobfuscatedThrottlingParameter);
 

extractor/src/main/java/org/schabi/newpipe/extractor/utils/Parser.java

@@ -91,22 +91,19 @@ public static Matcher matchMultiplePatterns(final Pattern[] patterns, final Stri
             if (matcher.find()) {
                 return matcher;
             } else if (exception == null) {
-                // only pass input to exception message when it is not too long
-                if (input.length() > 1024) {
-                    exception = new RegexException("Failed to find pattern \"" + pattern.pattern()
-                            + "\"");
-                } else {
-                    exception = new RegexException("Failed to find pattern \"" + pattern.pattern()
-                            + "\" inside of \"" + input + "\"");
-                }
+                exception = new RegexException("Failed to find pattern \"" + pattern.pattern()
+                    + "\""
+                    // only pass input to exception message when it is not too long
+                    + (input.length() <= 1000
+                    ? "inside of \"" + input + "\""
+                    : "")
+                );
             }
         }
 
-        if (exception == null) {
-            throw new RegexException("Empty patterns array passed to matchMultiplePatterns");
-        } else {
-            throw exception;
-        }
+        throw exception != null
+            ? exception
+            : new RegexException("Empty patterns array passed to matchMultiplePatterns");
     }
 
     public static boolean isMatch(final String pattern, final String input) {

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

@@ -1,21 +1,31 @@
 package org.schabi.newpipe.extractor.services.youtube;
 
+import static org.junit.jupiter.api.Assertions.assertDoesNotThrow;
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
-import static org.junit.jupiter.api.Assertions.fail;
 
+import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.function.Executable;
 import org.schabi.newpipe.extractor.InitNewPipeTest;
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 
+import java.util.Arrays;
+import java.util.stream.Stream;
+
+@Disabled("Throttling parameter deobfuscation is currently not functional, "
+    + "see https://github.com/TeamNewPipe/NewPipeExtractor/issues/1339")
 class YoutubeThrottlingParameterDeobfuscationTest implements InitYoutubeTest {
     @BeforeEach
     void beforeEach() {
         InitNewPipeTest.initEmpty();
         YoutubeTestsUtils.ensureStateless();
     }
 
+
     @Test
     void testExtractFunction__success() {
         InitNewPipeTest.initNewPipe(getClass(), "extractSuccess");
@@ -24,17 +34,15 @@ void testExtractFunction__success() {
 
         final String obfuscatedUrl = "https://r6---sn-4g5ednek.googlevideo.com/videoplayback?expire=1626562120&ei=6AnzYO_YBpql1gLGkb_IBQ&ip=127.0.0.1&id=o-ANhBEf36Z5h-8U9DDddtPDqtS0ZNwf0XJAAigudKI2uI&itag=278&aitags=133%2C134%2C135%2C136%2C137%2C160%2C242%2C243%2C244%2C247%2C248%2C278&source=youtube&requiressl=yes&vprv=1&mime=video%2Fwebm&ns=TvecOReN0vPuXb3j_zq157IG&gir=yes&clen=2915100&dur=270.203&lmt=1608157174907785&keepalive=yes&fexp=24001373,24007246&c=WEB&txp=5535432&n=N9BWSTFT7vvBJrvQ&sparams=expire%2Cei%2Cip%2Cid%2Caitags%2Csource%2Crequiressl%2Cvprv%2Cmime%2Cns%2Cgir%2Cclen%2Cdur%2Clmt&alr=yes&sig=AOq0QJ8wRQIgW6XnUDKPDSxiT0_KE_tDDMpcaCJl2Un5p0Fu9qZNQGkCIQDWxsDHi_s2BEmRqIbd1C5g_gzfihB7RZLsScKWNMwzzA%3D%3D&cpn=9r2yt3BqcYmeb2Yu&cver=2.20210716.00.00&redirect_counter=1&cm2rm=sn-4g5ezy7s&cms_redirect=yes&mh=Y5&mm=34&mn=sn-4g5ednek&ms=ltu&mt=1626540524&mv=m&mvi=6&pl=43&lsparams=mh,mm,mn,ms,mv,mvi,pl&lsig=AG3C_xAwRQIhAIUzxTn9Vw1-vm-_7OQ5-0h1M6AZsY9Bx1FlCCTeMICzAiADtGggbn4Znsrh2EnvyOsGnYdRGcbxn4mW9JMOQiInDQ%3D%3D&range=259165-480735&rn=11&rbuf=20190";
 
-        for (final String videoId : videoIds) {
-            try {
-                final String deobfuscatedUrl =
-                        YoutubeJavaScriptPlayerManager.getUrlWithThrottlingParameterDeobfuscated(
-                                videoId, obfuscatedUrl);
-                assertNotEquals(obfuscatedUrl, deobfuscatedUrl);
-            } catch (final Exception e) {
-                fail("Failed to extract throttling parameter deobfuscation function or run its code for video "
-                        + videoId, e);
-            }
-        }
+        Assertions.assertAll(
+            Arrays.stream(videoIds)
+                .flatMap(videoId -> {
+                    final String deobfuscatedUrl =
+                        assertDoesNotThrow(() -> YoutubeJavaScriptPlayerManager.getUrlWithThrottlingParameterDeobfuscated(
+                            videoId, obfuscatedUrl));
+                    return assertDeobfuscation(obfuscatedUrl, deobfuscatedUrl);
+                })
+        );
     }
 
     @Test
@@ -48,7 +56,14 @@ void testDecode__success() throws ParsingException {
                         "jE1USQrs1rw", obfuscatedUrl);
         // The deobfuscation function changes over time, so we just check if the corresponding
         // parameter changed
-        assertNotEquals(obfuscatedUrl, deobfuscatedUrl);
+        Assertions.assertAll(assertDeobfuscation(obfuscatedUrl, deobfuscatedUrl));
+    }
+
+    private Stream<Executable> assertDeobfuscation(final String obfuscatedUrl, final String deobfuscatedUrl) {
+        return Stream.of(
+            () -> assertNotEquals(obfuscatedUrl, deobfuscatedUrl),
+            () -> assertFalse(deobfuscatedUrl.contains("&n=&"), "Extracted n parameter is empty for " + deobfuscatedUrl)
+        );
     }
 
     @Test