Add and use bitmap-to-slice-or-set comparison functions

The generation of slices from things, and use of reflect.DeepEqual to compare
the slices, is a lot more expensive than it needs to be. Omitting it removes most
of the runtime of the marshal tests.

roaring/roaring.go

@@ -5756,7 +5756,37 @@ func xorBitmapRun(a, b *Container) *Container {
 	return output
 }
 
-// CompareEquality is used mostly in test cases to confirm that two bitmaps came
+// CompareBitmapSlice checks whether a bitmap has the same values in it
+// that a provided slice does.
+func CompareBitmapSlice(b *Bitmap, vals []uint64) (bool, error) {
+	count := b.Count()
+	if count != uint64(len(vals)) {
+		return false, fmt.Errorf("length mismatch: bitmap has %d bits, slice has %d", count, len(vals))
+	}
+	for _, v := range vals {
+		if !b.Contains(v) {
+			return false, fmt.Errorf("bitmap lacks expected value %d", v)
+		}
+	}
+	return true, nil
+}
+
+// CompareBitmapMap checks whether a bitmap has the same values in it
+// that a provided map[uint64]struct{} has as keys.
+func CompareBitmapMap(b *Bitmap, vals map[uint64]struct{}) (bool, error) {
+	count := b.Count()
+	if count != uint64(len(vals)) {
+		return false, fmt.Errorf("length mismatch: bitmap has %d bits, map has %d", count, len(vals))
+	}
+	for v := range vals {
+		if !b.Contains(v) {
+			return false, fmt.Errorf("bitmap lacks expected value %d", v)
+		}
+	}
+	return true, nil
+}
+
+// BitwiseEqual is used mostly in test cases to confirm that two bitmaps came
 // out the same. It does not expect corresponding opN, or OpWriter, but expects
 // identical bit contents. It does not expect identical representations; a bitmap
 // container can be identical to an array container. It returns a boolean value,

roaring/roaring_test.go

@@ -1570,14 +1570,12 @@ func testBitmapMarshalQuick(t *testing.T, n int, min, max uint64, sorted bool) {
 				t.Fatal(err)
 			}
 
-			// Verify the original bitmap has the correct set of values.
-			if exp, got := generator.Uint64SetSlice(set), bm.Slice(); !reflect.DeepEqual(exp, got) {
-				t.Fatalf("mismatch: %s\n\nexp=%+v\n\ngot=%+v\n\n", diff(exp, got), exp, got)
+			if _, err := roaring.CompareBitmapMap(bm, set); err != nil {
+				t.Fatalf("source mismatch: %v", err)
 			}
 
-			// Verify the bitmap loaded with the ops log has the correct set of values.
-			if exp, got := generator.Uint64SetSlice(set), bm2.Slice(); !reflect.DeepEqual(exp, got) {
-				t.Fatalf("mismatch: %s\n\nexp=%+v\n\ngot=%+v\n\n", diff(exp, got), exp, got)
+			if _, err := roaring.CompareBitmapMap(bm2, set); err != nil {
+				t.Fatalf("unmarshalled mismatch: %v", err)
 			}
 		}