refactor: extract shared ItTestSupport helper in integration-tests

integration-tests/src/test/java/io/github/dfa1/zstd/it/ItTestSupport.java

@@ -0,0 +1,30 @@
+package io.github.dfa1.zstd.it;
+
+import io.github.dfa1.zstd.Zstd;
+
+import java.util.Random;
+
+final class ItTestSupport {
+
+    static final int[] LEVELS = {
+        Zstd.minCompressionLevel(), 1, Zstd.defaultCompressionLevel(), Zstd.maxCompressionLevel()
+    };
+
+    static byte[] random(Random r, int size) {
+        byte[] b = new byte[size];
+        r.nextBytes(b);
+        return b;
+    }
+
+    static byte[] compressible(Random r, int size) {
+        byte[] b = new byte[size];
+        for (int i = 0; i < size; i++) {
+            b[i] = (byte) ((i % 13 == 0) ? r.nextInt(256) : 'a' + (i % 8));
+        }
+        return b;
+    }
+
+    private ItTestSupport() {
+        // no instances
+    }
+}

integration-tests/src/test/java/io/github/dfa1/zstd/it/ZstdInteropExtrasTest.java

@@ -27,6 +27,7 @@
 import java.util.Random;
 import java.util.stream.Stream;
 
+import static io.github.dfa1.zstd.it.ItTestSupport.random;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
@@ -294,11 +295,5 @@ private static void writeInChunks(java.io.OutputStream out, byte[] data) throws
                 out.flush();
             }
         }
-
-        private static byte[] random(Random r, int size) {
-            byte[] b = new byte[size];
-            r.nextBytes(b);
-            return b;
-        }
     }
 }

integration-tests/src/test/java/io/github/dfa1/zstd/it/ZstdJniInteropTest.java

@@ -23,6 +23,9 @@
 import java.util.Random;
 import java.util.stream.Stream;
 
+import static io.github.dfa1.zstd.it.ItTestSupport.LEVELS;
+import static io.github.dfa1.zstd.it.ItTestSupport.compressible;
+import static io.github.dfa1.zstd.it.ItTestSupport.random;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /// Format-compatibility tests: frames produced by the reference zstd-jni binding
@@ -35,10 +38,9 @@ static Stream<Arguments> payloadsAndLevels() {
         Random r = new Random(0xABCD);
         List<Arguments> cases = new ArrayList<>();
         int[] sizes = {0, 1, 1024, 64 * 1024, 1024 * 1024};
-        int[] levels = {Zstd.minCompressionLevel(), 1, Zstd.defaultCompressionLevel(), Zstd.maxCompressionLevel()};
         for (int size : sizes) {
             byte[] data = size % 2 == 0 ? compressible(r, size) : random(r, size);
-            for (int level : levels) {
+            for (int level : LEVELS) {
                 cases.add(Arguments.of(level, data));
             }
         }
@@ -171,18 +173,4 @@ private byte[] sample(int i) {
                     .getBytes(StandardCharsets.UTF_8);
         }
     }
-
-    private static byte[] random(Random r, int size) {
-        byte[] b = new byte[size];
-        r.nextBytes(b);
-        return b;
-    }
-
-    private static byte[] compressible(Random r, int size) {
-        byte[] b = new byte[size];
-        for (int i = 0; i < size; i++) {
-            b[i] = (byte) ((i % 13 == 0) ? r.nextInt(256) : 'a' + (i % 8));
-        }
-        return b;
-    }
 }