test: add edge cases for ByteStringUtil

Author: bevzzz

src/main/java/io/weaviate/client6/v1/internal/grpc/ByteStringUtil.java

@@ -57,47 +57,58 @@ public static ByteString encodeVectorMulti(float[][] vectors) {
   }
 
   /**
-   * Decode ByteString to float[].
+   * Decode ByteString to {@code float[]}.
    *
    * @throws IllegalArgumentException if ByteString size is not
    *                                  a multiple of {@link Float#BYTES}.
    */
   public static float[] decodeVectorSingle(ByteString bs) {
     if (bs.size() % Float.BYTES != 0) {
       throw new IllegalArgumentException(
-          "ByteString is size " + bs.size() + ", not a multiple of " + String.valueOf(Float.BYTES) + " (Float.BYTES)");
+          "ByteString size " + bs.size() + " is not a multiple of " + String.valueOf(Float.BYTES) + " (Float.BYTES)");
     }
     float[] vector = new float[bs.size() / Float.BYTES];
     bs.asReadOnlyByteBuffer().order(BYTE_ORDER).asFloatBuffer().get(vector);
     return vector;
   }
 
   /**
-   * Decode ByteString to float[][].
+   * Decode ByteString to {@code float[][]}.
    *
-   * @throws IllegalArgumentException if ByteString size is not
-   *                                  a multiple of {@link Float#BYTES}.
+   * <p>
+   * The expected structure of the byte string of total size N is:
+   * <ul>
+   * <li>[2 bytes]: dimensionality of the inner vector ({@code dim})
+   * <li>[N-2 bytes]: concatenated inner vectors. N-2 must be a multiple of
+   * {@code Float.BYTES * dim}
+   * </ul>
+   *
+   * @throws IllegalArgumentException if ByteString is not of a valid size.
    */
   public static float[][] decodeVectorMulti(ByteString bs) {
     if (bs == null || bs.size() == 0) {
       return new float[0][0];
     }
 
     ByteBuffer buf = bs.asReadOnlyByteBuffer().order(BYTE_ORDER);
+    short dim = buf.getShort(); // advances current position
+    if (dim == 0) {
+      return new float[0][0];
+    }
 
-    // Dimensions are encoded in the first 2 bytes.
-    short dimensions = buf.getShort(); // advances current position
-
-    // TODO: throw IllegalArgumentException if fbuf.remaining not a multile of
-    // Float.BYTES
-    FloatBuffer fbuf = buf.asFloatBuffer();
-    int n = fbuf.remaining() / dimensions; // fbuf size is buf / Float.BYTES
+    FloatBuffer fbuf = buf.asFloatBuffer(); // fbuf size is buf / Float.BYTES
+    if (fbuf.remaining() % dim != 0) {
+      throw new IllegalArgumentException(
+          "Remaing ByteString size " + fbuf.remaining() + " is not a multiple of " + dim
+              + " (dim)");
+    }
+    int n = fbuf.remaining() / dim;
 
     // Reading from buffer advances current position,
     // so we always read from offset=0.
-    float[][] vectors = new float[n][dimensions];
+    float[][] vectors = new float[n][dim];
     for (int i = 0; i < n; i++) {
-      fbuf.get(vectors[i], 0, dimensions);
+      fbuf.get(vectors[i], 0, dim);
     }
     return vectors;
   }

src/test/java/io/weaviate/client6/v1/internal/grpc/ByteStringUtilTest.java

@@ -54,4 +54,43 @@ public void test_decodeUuid() {
     String got = ByteStringUtil.decodeUuid(ByteString.copyFrom(bytes)).toString();
     assertEquals(want, got);
   }
+
+  @Test
+  public void test_decodeVector_1d_empty() {
+    byte[] bytes = new byte[0];
+    float[] got = ByteStringUtil.decodeVectorSingle(ByteString.copyFrom(bytes));
+    assertEquals(0, got.length);
+  }
+
+  @Test
+  public void test_decodeVector_2d_empty() {
+    byte[] bytes = new byte[0];
+    float[][] got = ByteStringUtil.decodeVectorMulti(ByteString.copyFrom(bytes));
+    assertEquals(0, got.length);
+  }
+
+  @Test
+  public void test_decodeVector_2d_dim_zero() {
+    byte[] bytes = new byte[] { 0, 0 };
+    float[][] got = ByteStringUtil.decodeVectorMulti(ByteString.copyFrom(bytes));
+    assertEquals(0, got.length);
+  }
+
+  @Test(expected = IllegalArgumentException.class)
+  public void test_decodeVector_1d_illegal() {
+    byte[] bytes = new byte[Float.BYTES - 1]; // must be a multiple of Float.BYTES
+    ByteStringUtil.decodeVectorSingle(ByteString.copyFrom(bytes));
+  }
+
+  @Test(expected = IllegalArgumentException.class)
+  public void test_decodeVector_2d_illegal() {
+    // The first Short.BYTES is the dimensionality of each array.
+    // The size of the rest must be a multiple of Float.BYTES * dimensionality.
+    var dimensionality = 5;
+    byte[] bytes = new byte[Short.BYTES + (Float.BYTES * dimensionality - 1)];
+    bytes[0] = 0;
+    bytes[1] = (byte) dimensionality;
+
+    ByteStringUtil.decodeVectorMulti(ByteString.copyFrom(bytes));
+  }
 }