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fix: complete test coverage for g:c:spanner::Timestamp (googleapis/go…
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…ogle-cloud-cpp-spanner#1190)

* Add test cases for some previously unexercised code paths
* Remove one always-unreachable overflow-detection code path
* Another overflow-detection code path is unreachable when
  tm_year is only 32-bits (which is usually the case), so we
  can't hit 100% coverage
* Fix one bug with creating a `Timestamp` from a `time_point`
  with sub-nanosecond precision, and add test case.
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@devbww
devbww authored Jan 11, 2020
1 parent 4608627 commit 05fe14e
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Showing 2 changed files with 151 additions and 67 deletions.
21 changes: 12 additions & 9 deletions google/cloud/spanner/timestamp.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -209,6 +209,9 @@ StatusOr<Timestamp> Timestamp::FromRFC3339(std::string const& s) {

std::intmax_t const sec = TimeZ(tm);
constexpr auto kDestType = "UTC offset";
// Note: These overflow conditions are unreachable when tm.tm_year is only
// 32 bits (as is typically the case) as the max/min possible `sec` value
// plus/minus the max/min possible `utc_offset_secs` cannot oveflow 64 bits.
if (utc_offset_secs >= 0) {
if (sec > std::numeric_limits<std::intmax_t>::max() - utc_offset_secs) {
return PositiveOverflow(kDestType);
Expand Down Expand Up @@ -328,8 +331,13 @@ StatusOr<Timestamp> Timestamp::FromRatio(std::intmax_t const count,
sec *= numerator;

auto sscount = count - sec * denominator / numerator;
auto nsec = sscount * kNanosPerSecond / denominator * numerator;
return FromCounts(sec, nsec);
if (denominator > kNanosPerSecond) {
auto const divider = denominator / kNanosPerSecond;
if (sscount < 0) sscount -= divider - 1; // floor
return FromCounts(sec, sscount / divider * numerator);
}
auto const multiplier = kNanosPerSecond / denominator;
return FromCounts(sec, sscount * multiplier * numerator);
}

// [sec, nsec] => bounded (count * numerator/denominator) seconds.
Expand All @@ -356,15 +364,10 @@ StatusOr<std::intmax_t> Timestamp::ToRatio(
count *= denominator;

auto ncount = nsec_ / numerator;
if (denominator <= kNanosPerSecond) {
if (denominator < kNanosPerSecond) {
ncount /= kNanosPerSecond / denominator;
} else {
auto const multiplier = denominator / kNanosPerSecond;
if (ncount > std::numeric_limits<std::intmax_t>::max() / multiplier) {
// Might be premature to declare overflow on an intermediate value.
return PositiveOverflow(kDestType);
}
ncount *= multiplier;
ncount *= denominator / kNanosPerSecond;
}

if (count > std::numeric_limits<std::intmax_t>::max() - ncount) {
Expand Down
197 changes: 139 additions & 58 deletions google/cloud/spanner/timestamp_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,8 @@
#include <google/protobuf/timestamp.pb.h>
#include <gmock/gmock.h>
#include <cstdint>
#include <limits>
#include <sstream>

namespace google {
namespace cloud {
Expand All @@ -25,6 +27,16 @@ namespace {

using ::testing::HasSubstr;

// Note: You can validate the std::time_t/string conversions using date(1).
// $ date --utc +%Y-%m-%dT%H:%M:%SZ --date=@1561135942
// 2019-06-21T16:52:22Z
// $ date +%s --date=2019-06-21T16:52:22Z
// 1561135942

// Assumes the system_clock epoch is hour-aligned with the Unix epoch.
auto const kUnixEpoch = std::chrono::time_point_cast<std::chrono::hours>(
std::chrono::system_clock::from_time_t(0));

google::protobuf::Timestamp MakeProtoTimestamp(std::int64_t seconds,
std::int32_t nanos) {
google::protobuf::Timestamp proto;
Expand Down Expand Up @@ -85,12 +97,13 @@ TEST(Timestamp, RelationalOperators) {
internal::TimestampFromProto(MakeProtoTimestamp(1576030524, 611422667)));
}

TEST(Timestamp, OutputStreaming) {
std::ostringstream os;
os << internal::TimestampFromProto(MakeProtoTimestamp(1561135942, 123456789));
EXPECT_EQ("2019-06-21T16:52:22.123456789Z", os.str());
}

TEST(Timestamp, FromRFC3339) {
// Note: You can validate std::time_t/string conversions using date(1).
// $ date --utc +%Y-%m-%dT%H:%M:%SZ --date=@1561135942
// 2019-06-21T16:52:22Z
// $ date +%s --date=2019-06-21T16:52:22Z
// 1561135942
EXPECT_EQ(internal::TimestampFromProto(MakeProtoTimestamp(1561135942, 0)),
internal::TimestampFromRFC3339("2019-06-21T16:52:22Z").value());
EXPECT_EQ(
Expand Down Expand Up @@ -290,7 +303,7 @@ TEST(Timestamp, ToRFC3339Limit) {
}

TEST(Timestamp, FromProto) {
google::protobuf::Timestamp proto = MakeProtoTimestamp(0, 0);
auto proto = MakeProtoTimestamp(0, 0);
EXPECT_EQ("1970-01-01T00:00:00Z",
internal::TimestampToRFC3339(internal::TimestampFromProto(proto)));

Expand All @@ -307,6 +320,33 @@ TEST(Timestamp, FromProto) {
internal::TimestampToRFC3339(internal::TimestampFromProto(proto)));
}

TEST(Timestamp, FromProtoLimit) {
// Least, normalized protobuf::Timestamp (but beyond documented range).
auto proto = internal::TimestampToProto(internal::TimestampFromProto(
MakeProtoTimestamp(std::numeric_limits<std::int64_t>::min(), 0)));
EXPECT_EQ(std::numeric_limits<std::int64_t>::min(), proto.seconds());
EXPECT_EQ(0, proto.nanos());

// Trying to go one nanosecond earlier still produces the least-normalized.
proto = internal::TimestampToProto(internal::TimestampFromProto(
MakeProtoTimestamp(std::numeric_limits<std::int64_t>::min(), 0 - 1)));
EXPECT_EQ(std::numeric_limits<std::int64_t>::min(), proto.seconds());
EXPECT_EQ(0, proto.nanos());

// Largest, normalized protobuf::Timestamp (but beyond documented range).
proto = internal::TimestampToProto(internal::TimestampFromProto(
MakeProtoTimestamp(std::numeric_limits<std::int64_t>::max(), 999999999)));
EXPECT_EQ(std::numeric_limits<std::int64_t>::max(), proto.seconds());
EXPECT_EQ(999999999, proto.nanos());

// Trying to go one nanosecond later still produces the largest-normalized.
proto = internal::TimestampToProto(
internal::TimestampFromProto(MakeProtoTimestamp(
std::numeric_limits<std::int64_t>::max(), 999999999 + 1)));
EXPECT_EQ(std::numeric_limits<std::int64_t>::max(), proto.seconds());
EXPECT_EQ(999999999, proto.nanos());
}

TEST(Timestamp, ToProto) {
auto proto = internal::TimestampToProto(
internal::TimestampFromRFC3339("1970-01-01T00:00:00.000000000Z").value());
Expand All @@ -330,138 +370,179 @@ TEST(Timestamp, ToProto) {
}

TEST(Timestamp, FromChrono) { // i.e., MakeTimestamp(sys_time<Duration>)
// A chrono duration that can hold values beyond the range of Timestamp.
using big_minutes = std::chrono::duration<std::int64_t, std::ratio<60>>;

// Assumes the system_clock epoch is hour-aligned with the Unix epoch.
auto const unix_epoch = std::chrono::time_point_cast<std::chrono::hours>(
std::chrono::system_clock::from_time_t(0));

auto const tp1 = unix_epoch + std::chrono::seconds(2123456789) +
auto const tp1 = kUnixEpoch + std::chrono::seconds(2123456789) +
std::chrono::nanoseconds(123456789);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(2123456789, 123456789)),
MakeTimestamp(tp1).value());

auto const tp2 = unix_epoch + std::chrono::seconds(2123456789) +
auto const tp2 = kUnixEpoch + std::chrono::seconds(2123456789) +
std::chrono::microseconds(123456);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(2123456789, 123456000)),
MakeTimestamp(tp2).value());

auto const tp3 = unix_epoch + std::chrono::seconds(2123456789) +
auto const tp3 = kUnixEpoch + std::chrono::seconds(2123456789) +
std::chrono::milliseconds(123);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(2123456789, 123000000)),
MakeTimestamp(tp3).value());

auto const tp4 = unix_epoch + std::chrono::minutes(2123456789);
auto const tp4 = kUnixEpoch + std::chrono::minutes(2123456789);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(2123456789LL * 60, 0)),
MakeTimestamp(tp4).value());

auto const tp5 = unix_epoch + std::chrono::hours(2123456789);
auto const tp5 = kUnixEpoch + std::chrono::hours(2123456789);
EXPECT_EQ(internal::TimestampFromProto(
MakeProtoTimestamp(2123456789LL * 60 * 60, 0)),
MakeTimestamp(tp5).value());

auto const tp_big_pos = unix_epoch + big_minutes(153722867280912931LL);
auto const ts_big_pos = MakeTimestamp(tp_big_pos);
EXPECT_FALSE(ts_big_pos.ok());
EXPECT_THAT(ts_big_pos.status().message(), HasSubstr("positive overflow"));

auto const tp6 = unix_epoch - std::chrono::seconds(2123456789) +
auto const tp6 = kUnixEpoch - std::chrono::seconds(2123456789) +
std::chrono::nanoseconds(123456789);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(-2123456789, 123456789)),
MakeTimestamp(tp6).value());

auto const tp7 = unix_epoch - std::chrono::seconds(2123456789) +
auto const tp7 = kUnixEpoch - std::chrono::seconds(2123456789) +
std::chrono::microseconds(123456);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(-2123456789, 123456000)),
MakeTimestamp(tp7).value());

auto const tp8 = unix_epoch - std::chrono::seconds(2123456789) +
auto const tp8 = kUnixEpoch - std::chrono::seconds(2123456789) +
std::chrono::milliseconds(123);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(-2123456789, 123000000)),
MakeTimestamp(tp8).value());

auto const tp9 = unix_epoch - std::chrono::minutes(2123456789);
auto const tp9 = kUnixEpoch - std::chrono::minutes(2123456789);
EXPECT_EQ(
internal::TimestampFromProto(MakeProtoTimestamp(-2123456789LL * 60, 0)),
MakeTimestamp(tp9).value());

auto const tp10 = unix_epoch - std::chrono::hours(2123456789);
auto const tp10 = kUnixEpoch - std::chrono::hours(2123456789);
EXPECT_EQ(internal::TimestampFromProto(
MakeProtoTimestamp(-2123456789LL * 60 * 60, 0)),
MakeTimestamp(tp10).value());

auto const tp_big_neg = unix_epoch - big_minutes(153722867280912931LL);
auto const ts_big_neg = MakeTimestamp(tp_big_neg);
EXPECT_FALSE(ts_big_neg.ok());
EXPECT_THAT(ts_big_neg.status().message(), HasSubstr("negative overflow"));
// A chrono duration that can hold values beyond the resolution of Timestamp.
using picoseconds = std::chrono::duration<std::int64_t, std::pico>;

auto const tp11 =
kUnixEpoch + std::chrono::seconds(123) + picoseconds(123456789);
EXPECT_EQ(internal::TimestampFromProto(MakeProtoTimestamp(123, 123456)),
MakeTimestamp(tp11).value());

auto const tp12 =
kUnixEpoch - std::chrono::seconds(123) + picoseconds(123456789);
EXPECT_EQ(internal::TimestampFromProto(MakeProtoTimestamp(-123, 123456)),
MakeTimestamp(tp12).value());
}

TEST(Timestamp, ToChrono) { // i.e., Timestamp::get<sys_time<Duration>>()
// Assumes the system_clock epoch is hour-aligned with the Unix epoch.
auto const epoch = std::chrono::time_point_cast<std::chrono::seconds>(
std::chrono::system_clock::from_time_t(0));
TEST(Timestamp, FromChronoOverflow) {
// A chrono duration that can hold values beyond the range of Timestamp.
using big_minutes = std::chrono::duration<std::int64_t, std::ratio<60>>;

auto const tp1 = kUnixEpoch + big_minutes(153722867280912931);
auto const ts1 = MakeTimestamp(tp1);
EXPECT_FALSE(ts1.ok());
EXPECT_THAT(ts1.status().message(), HasSubstr("positive overflow"));

auto const tp2 = kUnixEpoch - big_minutes(153722867280912931);
auto const ts2 = MakeTimestamp(tp2);
EXPECT_FALSE(ts2.ok());
EXPECT_THAT(ts2.status().message(), HasSubstr("negative overflow"));
}

TEST(Timestamp, ToChrono) { // i.e., Timestamp::get<sys_time<Duration>>()
auto const ts_pos =
internal::TimestampFromProto(MakeProtoTimestamp(2123456789, 123456789));

auto const tp1 = epoch + std::chrono::seconds(2123456789) +
auto const tp1 = kUnixEpoch + std::chrono::seconds(2123456789) +
std::chrono::nanoseconds(123456789);
EXPECT_EQ(tp1, ts_pos.get<sys_time<std::chrono::nanoseconds>>().value());

auto const tp2 = epoch + std::chrono::seconds(2123456789) +
auto const tp2 = kUnixEpoch + std::chrono::seconds(2123456789) +
std::chrono::microseconds(123456);
EXPECT_EQ(tp2, ts_pos.get<sys_time<std::chrono::microseconds>>().value());

auto const tp3 =
epoch + std::chrono::seconds(2123456789) + std::chrono::milliseconds(123);
auto const tp3 = kUnixEpoch + std::chrono::seconds(2123456789) +
std::chrono::milliseconds(123);
EXPECT_EQ(tp3, ts_pos.get<sys_time<std::chrono::milliseconds>>().value());

auto const tp4 = epoch + std::chrono::seconds(2123456789);
auto const tp4 = kUnixEpoch + std::chrono::seconds(2123456789);
EXPECT_EQ(tp4, ts_pos.get<sys_time<std::chrono::seconds>>().value());

auto const tp5 = epoch + std::chrono::hours(2123456789 / 60 / 60);
auto const tp5 = kUnixEpoch + std::chrono::hours(2123456789 / 60 / 60);
EXPECT_EQ(tp5, ts_pos.get<sys_time<std::chrono::hours>>().value());

auto const ts_big_pos =
internal::TimestampFromProto(MakeProtoTimestamp(20000000000, 0));
auto const tp_big_pos = ts_big_pos.get<sys_time<std::chrono::nanoseconds>>();
EXPECT_FALSE(tp_big_pos.ok());
EXPECT_THAT(tp_big_pos.status().message(), HasSubstr("positive overflow"));

auto const ts_neg =
internal::TimestampFromProto(MakeProtoTimestamp(-2123456789, 123456789));

auto const tp6 = epoch - std::chrono::seconds(2123456789) +
auto const tp6 = kUnixEpoch - std::chrono::seconds(2123456789) +
std::chrono::nanoseconds(123456789);
EXPECT_EQ(tp6, ts_neg.get<sys_time<std::chrono::nanoseconds>>().value());

auto const tp7 = epoch - std::chrono::seconds(2123456789) +
auto const tp7 = kUnixEpoch - std::chrono::seconds(2123456789) +
std::chrono::microseconds(123456);
EXPECT_EQ(tp7, ts_neg.get<sys_time<std::chrono::microseconds>>().value());

auto const tp8 =
epoch - std::chrono::seconds(2123456789) + std::chrono::milliseconds(123);
auto const tp8 = kUnixEpoch - std::chrono::seconds(2123456789) +
std::chrono::milliseconds(123);
EXPECT_EQ(tp8, ts_neg.get<sys_time<std::chrono::milliseconds>>().value());

auto const tp9 = epoch - std::chrono::seconds(2123456789);
auto const tp9 = kUnixEpoch - std::chrono::seconds(2123456789);
EXPECT_EQ(tp9, ts_neg.get<sys_time<std::chrono::seconds>>().value());

auto const tp10 = epoch - std::chrono::hours(2123456789 / 60 / 60);
auto const tp10 = kUnixEpoch - std::chrono::hours(2123456789 / 60 / 60);
EXPECT_EQ(tp10, ts_neg.get<sys_time<std::chrono::hours>>().value());

auto const ts_big_neg =
// The limit of a 64-bit count of nanoseconds (assuming the system_clock
// epoch is the Unix epoch).
auto const ts11 =
internal::TimestampFromProto(MakeProtoTimestamp(9223372036, 854775807));
auto const tp11 = kUnixEpoch + std::chrono::seconds(9223372036) +
std::chrono::nanoseconds(854775807);
EXPECT_EQ(tp11, ts11.get<sys_time<std::chrono::nanoseconds>>().value());

// A chrono duration that can hold values beyond the resolution of Timestamp.
using picoseconds = std::chrono::duration<std::int64_t, std::pico>;

auto const ts12 =
internal::TimestampFromProto(MakeProtoTimestamp(123, 123456));
auto const tp12 =
kUnixEpoch + std::chrono::seconds(123) + picoseconds(123456000);
EXPECT_EQ(tp12, ts12.get<sys_time<picoseconds>>().value());

auto const ts13 =
internal::TimestampFromProto(MakeProtoTimestamp(-123, 123456));
auto const tp13 =
kUnixEpoch - std::chrono::seconds(123) + picoseconds(123456000);
EXPECT_EQ(tp13, ts13.get<sys_time<picoseconds>>().value());
}

TEST(Timestamp, ToChronoOverflow) {
auto const ts1 =
internal::TimestampFromProto(MakeProtoTimestamp(20000000000, 0));
auto const tp1 = ts1.get<sys_time<std::chrono::nanoseconds>>();
EXPECT_FALSE(tp1.ok());
EXPECT_THAT(tp1.status().message(), HasSubstr("positive overflow"));

auto const ts2 =
internal::TimestampFromProto(MakeProtoTimestamp(-20000000000, 0));
auto const tp_big_neg = ts_big_neg.get<sys_time<std::chrono::nanoseconds>>();
EXPECT_FALSE(tp_big_neg.ok());
EXPECT_THAT(tp_big_neg.status().message(), HasSubstr("negative overflow"));
auto const tp2 = ts2.get<sys_time<std::chrono::nanoseconds>>();
EXPECT_FALSE(tp2.ok());
EXPECT_THAT(tp2.status().message(), HasSubstr("negative overflow"));

// One beyond the limit of a 64-bit count of nanoseconds (assuming the
// system_clock epoch is the Unix epoch). This overflow is detected in a
// different code path to the "positive overflow" above.
auto const ts3 =
internal::TimestampFromProto(MakeProtoTimestamp(9223372036, 854775808));
auto const tp3 = ts3.get<sys_time<std::chrono::nanoseconds>>();
EXPECT_FALSE(tp3.ok());
EXPECT_THAT(tp3.status().message(), HasSubstr("positive overflow"));
}

} // namespace
Expand Down

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