pitrou commented on code in PR #14191:
URL: https://github.com/apache/arrow/pull/14191#discussion_r1048503894
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cpp/src/arrow/util/rle_encoding_test.cc:
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@@ -173,6 +173,39 @@ TEST(BitArray, TestMixed) {
}
}
+// Writes 'num_vals' values with width 'bit_width' and reads them back.
+static void TestPutValue(int bit_width, uint64_t num_vals) {
+ const uint64_t max = uint64_t(2) << (bit_width - 1);
+ num_vals = std::min(num_vals, max);
+ int len = static_cast<int>(bit_util::BytesForBits(bit_width * num_vals));
+ EXPECT_GT(len, 0);
+
+ std::vector<uint8_t> buffer(len);
+ bit_util::BitWriter writer(buffer.data(), len);
+ for (uint64_t i = max - num_vals; i < max; i++) {
+ bool result = writer.PutValue(i, bit_width);
+ EXPECT_TRUE(result);
+ }
+ writer.Flush();
+ EXPECT_EQ(writer.bytes_written(), len);
+
+ bit_util::BitReader reader(buffer.data(), len);
+ for (uint64_t i = max - num_vals; i < max; i++) {
+ int64_t val = 0;
+ bool result = reader.GetValue(bit_width, &val);
+ EXPECT_TRUE(result);
+ EXPECT_EQ(val, i);
+ }
+ EXPECT_EQ(reader.bytes_left(), 0);
+}
+
+TEST(BitUtil, RoundTripIntValues) {
+ for (int width = 1; width < 64; width++) {
Review Comment:
What do you mean? Testing that we are able to write 64-bit values makes
sense.
Perhaps you want something like:
```c++
// The max value representable in `bit_width` bits.
const uint64_t max = std::numeric_limits<uint64_t>::max() >> (64 -
bit_width);
```
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