Move BitUtils, RingBuffer test to coretests

The utilities are part of com.android.internal.util, but were
historically tested as part of the services.net tests. They were then
mistakenly moved to packages/modules/Connectivity with the rest of the
networking code, but actually belong in coretests.

Bug: 187935317
Test: atest FrameworksCoreTests
Change-Id: Ia4179ac3e25170e46b47133be0f5d4f1b24caf3d

2 files changed, 379 insertions, 0 deletions

diff --git a/core/tests/coretests/src/com/android/internal/util/BitUtilsTest.java b/core/tests/coretests/src/com/android/internal/util/BitUtilsTest.java
new file mode 100644
index 000000000000..fdba811f3eaa
--- /dev/null
+++ b/core/tests/coretests/src/com/android/internal/util/BitUtilsTest.java
@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.internal.util;
+
+import static com.android.internal.util.BitUtils.bytesToBEInt;
+import static com.android.internal.util.BitUtils.bytesToLEInt;
+import static com.android.internal.util.BitUtils.getUint16;
+import static com.android.internal.util.BitUtils.getUint32;
+import static com.android.internal.util.BitUtils.getUint8;
+import static com.android.internal.util.BitUtils.packBits;
+import static com.android.internal.util.BitUtils.uint16;
+import static com.android.internal.util.BitUtils.uint32;
+import static com.android.internal.util.BitUtils.uint8;
+import static com.android.internal.util.BitUtils.unpackBits;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.filters.SmallTest;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.nio.ByteBuffer;
+import java.util.Arrays;
+import java.util.Random;
+
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class BitUtilsTest {
+
+    @Test
+    public void testUnsignedByteWideningConversions() {
+        byte b0 = 0;
+        byte b1 = 1;
+        byte bm1 = -1;
+        assertEquals(0, uint8(b0));
+        assertEquals(1, uint8(b1));
+        assertEquals(127, uint8(Byte.MAX_VALUE));
+        assertEquals(128, uint8(Byte.MIN_VALUE));
+        assertEquals(255, uint8(bm1));
+        assertEquals(255, uint8((byte)255));
+    }
+
+    @Test
+    public void testUnsignedShortWideningConversions() {
+        short s0 = 0;
+        short s1 = 1;
+        short sm1 = -1;
+        assertEquals(0, uint16(s0));
+        assertEquals(1, uint16(s1));
+        assertEquals(32767, uint16(Short.MAX_VALUE));
+        assertEquals(32768, uint16(Short.MIN_VALUE));
+        assertEquals(65535, uint16(sm1));
+        assertEquals(65535, uint16((short)65535));
+    }
+
+    @Test
+    public void testUnsignedShortComposition() {
+        byte b0 = 0;
+        byte b1 = 1;
+        byte b2 = 2;
+        byte b10 = 10;
+        byte b16 = 16;
+        byte b128 = -128;
+        byte b224 = -32;
+        byte b255 = -1;
+        assertEquals(0x0000, uint16(b0, b0));
+        assertEquals(0xffff, uint16(b255, b255));
+        assertEquals(0x0a01, uint16(b10, b1));
+        assertEquals(0x8002, uint16(b128, b2));
+        assertEquals(0x01ff, uint16(b1, b255));
+        assertEquals(0x80ff, uint16(b128, b255));
+        assertEquals(0xe010, uint16(b224, b16));
+    }
+
+    @Test
+    public void testUnsignedIntWideningConversions() {
+        assertEquals(0, uint32(0));
+        assertEquals(1, uint32(1));
+        assertEquals(2147483647L, uint32(Integer.MAX_VALUE));
+        assertEquals(2147483648L, uint32(Integer.MIN_VALUE));
+        assertEquals(4294967295L, uint32(-1));
+        assertEquals(4294967295L, uint32((int)4294967295L));
+    }
+
+    @Test
+    public void testBytesToInt() {
+        assertEquals(0x00000000, bytesToBEInt(bytes(0, 0, 0, 0)));
+        assertEquals(0xffffffff, bytesToBEInt(bytes(255, 255, 255, 255)));
+        assertEquals(0x0a000001, bytesToBEInt(bytes(10, 0, 0, 1)));
+        assertEquals(0x0a000002, bytesToBEInt(bytes(10, 0, 0, 2)));
+        assertEquals(0x0a001fff, bytesToBEInt(bytes(10, 0, 31, 255)));
+        assertEquals(0xe0000001, bytesToBEInt(bytes(224, 0, 0, 1)));
+
+        assertEquals(0x00000000, bytesToLEInt(bytes(0, 0, 0, 0)));
+        assertEquals(0x01020304, bytesToLEInt(bytes(4, 3, 2, 1)));
+        assertEquals(0xffff0000, bytesToLEInt(bytes(0, 0, 255, 255)));
+    }
+
+    @Test
+    public void testUnsignedGetters() {
+        ByteBuffer b = ByteBuffer.allocate(4);
+        b.putInt(0xffff);
+
+        assertEquals(0x0, getUint8(b, 0));
+        assertEquals(0x0, getUint8(b, 1));
+        assertEquals(0xff, getUint8(b, 2));
+        assertEquals(0xff, getUint8(b, 3));
+
+        assertEquals(0x0, getUint16(b, 0));
+        assertEquals(0xffff, getUint16(b, 2));
+
+        b.rewind();
+        b.putInt(0xffffffff);
+        assertEquals(0xffffffffL, getUint32(b, 0));
+    }
+
+    @Test
+    public void testBitsPacking() {
+        BitPackingTestCase[] testCases = {
+            new BitPackingTestCase(0, ints()),
+            new BitPackingTestCase(1, ints(0)),
+            new BitPackingTestCase(2, ints(1)),
+            new BitPackingTestCase(3, ints(0, 1)),
+            new BitPackingTestCase(4, ints(2)),
+            new BitPackingTestCase(6, ints(1, 2)),
+            new BitPackingTestCase(9, ints(0, 3)),
+            new BitPackingTestCase(~Long.MAX_VALUE, ints(63)),
+            new BitPackingTestCase(~Long.MAX_VALUE + 1, ints(0, 63)),
+            new BitPackingTestCase(~Long.MAX_VALUE + 2, ints(1, 63)),
+        };
+        for (BitPackingTestCase tc : testCases) {
+            int[] got = unpackBits(tc.packedBits);
+            assertTrue(
+                    "unpackBits("
+                            + tc.packedBits
+                            + "): expected "
+                            + Arrays.toString(tc.bits)
+                            + " but got "
+                            + Arrays.toString(got),
+                    Arrays.equals(tc.bits, got));
+        }
+        for (BitPackingTestCase tc : testCases) {
+            long got = packBits(tc.bits);
+            assertEquals(
+                    "packBits("
+                            + Arrays.toString(tc.bits)
+                            + "): expected "
+                            + tc.packedBits
+                            + " but got "
+                            + got,
+                    tc.packedBits,
+                    got);
+        }
+
+        long[] moreTestCases = {
+            0, 1, -1, 23895, -908235, Long.MAX_VALUE, Long.MIN_VALUE, new Random().nextLong(),
+        };
+        for (long l : moreTestCases) {
+            assertEquals(l, packBits(unpackBits(l)));
+        }
+    }
+
+    static byte[] bytes(int b1, int b2, int b3, int b4) {
+        return new byte[] {b(b1), b(b2), b(b3), b(b4)};
+    }
+
+    static byte b(int i) {
+        return (byte) i;
+    }
+
+    static int[] ints(int... array) {
+        return array;
+    }
+
+    static class BitPackingTestCase {
+        final int[] bits;
+        final long packedBits;
+
+        BitPackingTestCase(long packedBits, int[] bits) {
+            this.bits = bits;
+            this.packedBits = packedBits;
+        }
+    }
+}
diff --git a/core/tests/coretests/src/com/android/internal/util/RingBufferTest.java b/core/tests/coretests/src/com/android/internal/util/RingBufferTest.java
new file mode 100644
index 000000000000..4497770ef40d
--- /dev/null
+++ b/core/tests/coretests/src/com/android/internal/util/RingBufferTest.java
@@ -0,0 +1,178 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.internal.util;
+
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.fail;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.test.filters.SmallTest;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@SmallTest
+@RunWith(AndroidJUnit4.class)
+public class RingBufferTest {
+
+    @Test
+    public void testEmptyRingBuffer() {
+        RingBuffer<String> buffer = new RingBuffer<>(String.class, 100);
+
+        assertArrayEquals(new String[0], buffer.toArray());
+    }
+
+    @Test
+    public void testIncorrectConstructorArguments() {
+        try {
+            RingBuffer<String> buffer = new RingBuffer<>(String.class, -10);
+            fail("Should not be able to create a negative capacity RingBuffer");
+        } catch (IllegalArgumentException expected) {
+        }
+
+        try {
+            RingBuffer<String> buffer = new RingBuffer<>(String.class, 0);
+            fail("Should not be able to create a 0 capacity RingBuffer");
+        } catch (IllegalArgumentException expected) {
+        }
+    }
+
+    @Test
+    public void testRingBufferWithNoWrapping() {
+        RingBuffer<String> buffer = new RingBuffer<>(String.class, 100);
+
+        buffer.append("a");
+        buffer.append("b");
+        buffer.append("c");
+        buffer.append("d");
+        buffer.append("e");
+
+        String[] expected = {"a", "b", "c", "d", "e"};
+        assertArrayEquals(expected, buffer.toArray());
+    }
+
+    @Test
+    public void testRingBufferWithCapacity1() {
+        RingBuffer<String> buffer = new RingBuffer<>(String.class, 1);
+
+        buffer.append("a");
+        assertArrayEquals(new String[]{"a"}, buffer.toArray());
+
+        buffer.append("b");
+        assertArrayEquals(new String[]{"b"}, buffer.toArray());
+
+        buffer.append("c");
+        assertArrayEquals(new String[]{"c"}, buffer.toArray());
+
+        buffer.append("d");
+        assertArrayEquals(new String[]{"d"}, buffer.toArray());
+
+        buffer.append("e");
+        assertArrayEquals(new String[]{"e"}, buffer.toArray());
+    }
+
+    @Test
+    public void testRingBufferWithWrapping() {
+        int capacity = 100;
+        RingBuffer<String> buffer = new RingBuffer<>(String.class, capacity);
+
+        buffer.append("a");
+        buffer.append("b");
+        buffer.append("c");
+        buffer.append("d");
+        buffer.append("e");
+
+        String[] expected1 = {"a", "b", "c", "d", "e"};
+        assertArrayEquals(expected1, buffer.toArray());
+
+        String[] expected2 = new String[capacity];
+        int firstIndex = 0;
+        int lastIndex = capacity - 1;
+
+        expected2[firstIndex] = "e";
+        for (int i = 1; i < capacity; i++) {
+            buffer.append("x");
+            expected2[i] = "x";
+        }
+        assertArrayEquals(expected2, buffer.toArray());
+
+        buffer.append("x");
+        expected2[firstIndex] = "x";
+        assertArrayEquals(expected2, buffer.toArray());
+
+        for (int i = 0; i < 10; i++) {
+            for (String s : expected2) {
+                buffer.append(s);
+            }
+        }
+        assertArrayEquals(expected2, buffer.toArray());
+
+        buffer.append("a");
+        expected2[lastIndex] = "a";
+        assertArrayEquals(expected2, buffer.toArray());
+    }
+
+    @Test
+    public void testGetNextSlot() {
+        int capacity = 100;
+        RingBuffer<DummyClass1> buffer = new RingBuffer<>(DummyClass1.class, capacity);
+
+        final DummyClass1[] actual = new DummyClass1[capacity];
+        final DummyClass1[] expected = new DummyClass1[capacity];
+        for (int i = 0; i < capacity; ++i) {
+            final DummyClass1 obj = buffer.getNextSlot();
+            obj.x = capacity * i;
+            actual[i] = obj;
+            expected[i] = new DummyClass1();
+            expected[i].x = capacity * i;
+        }
+        assertArrayEquals(expected, buffer.toArray());
+
+        for (int i = 0; i < capacity; ++i) {
+            if (actual[i] != buffer.getNextSlot()) {
+                fail("getNextSlot() should re-use objects if available");
+            }
+        }
+
+        RingBuffer<DummyClass2> buffer2 = new RingBuffer<>(DummyClass2.class, capacity);
+        assertNull("getNextSlot() should return null if the object can't be initiated "
+                + "(No nullary constructor)", buffer2.getNextSlot());
+
+        RingBuffer<DummyClass3> buffer3 = new RingBuffer<>(DummyClass3.class, capacity);
+        assertNull("getNextSlot() should return null if the object can't be initiated "
+                + "(Inaccessible class)", buffer3.getNextSlot());
+    }
+
+    public static final class DummyClass1 {
+        int x;
+
+        public boolean equals(Object o) {
+            if (o instanceof DummyClass1) {
+                final DummyClass1 other = (DummyClass1) o;
+                return other.x == this.x;
+            }
+            return false;
+        }
+    }
+
+    public static final class DummyClass2 {
+        public DummyClass2(int x) {}
+    }
+
+    private static final class DummyClass3 {}
+}