WiP: Implement first prototypes of all SOP commands for external binaries

external-sop/src/test/java/sop/external/JUtils.java

@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2023 Paul Schaub <vanitasvitae@fsfe.org>
+//
+// SPDX-License-Identifier: Apache-2.0
+
+package sop.external;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.fail;
+
+public class JUtils {
+
+    public static boolean arrayStartsWith(byte[] array, byte[] start) {
+        return arrayStartsWith(array, start, 0);
+    }
+
+    public static boolean arrayStartsWith(byte[] array, byte[] start, int offset) {
+        if (offset < 0) {
+            throw new IllegalArgumentException("Offset cannot be negative");
+        }
+
+        if (start.length + offset > array.length) {
+            return false;
+        }
+
+        for (int i = 0; i < start.length; i++) {
+            if (array[offset + i] != start[i]) {
+                return false;
+            }
+        }
+        return true;
+    }
+
+    public static void assertArrayStartsWith(byte[] array, byte[] start) {
+        if (!arrayStartsWith(array, start)) {
+            byte[] actual = new byte[Math.min(start.length, array.length)];
+            System.arraycopy(array, 0, actual, 0, actual.length);
+            fail("Array does not start with expected bytes.\n" +
+                    "Expected: <" + Arrays.toString(start) + ">\n" +
+                    "Actual: <" + Arrays.toString(actual) + ">");
+        }
+    }
+
+    public static void assertArrayStartsWith(byte[] array, byte[] start, int offset) {
+        if (!arrayStartsWith(array, start, offset)) {
+            byte[] actual = new byte[Math.min(start.length, array.length - offset)];
+            System.arraycopy(array, offset, actual, 0, actual.length);
+            fail("Array does not start with expected bytes at offset " + offset + ".\n" +
+                    "Expected: <" + Arrays.toString(start) + ">\n" +
+                    "Actual: <" + Arrays.toString(actual) + ">");
+        }
+    }
+}