fix: correct range validation in ParseRfc3339 (#220)

It was not accepting 59 as a valid minute, this bug was introduced in
the clang-tidy cleanup, and our tests validate that things *outside* the
valid ranges are correctly reported as errors, but not that things
*exactly* at the boundary conditions are reported as valid. Sigh.

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## v0.23.x - TBD
 
+## v0.22.1 - 2020-03
+
+* fix: correct range validation in ParseRfc3339 (#219) - the library incorrectly
+  rejected timestamps with '59' in the minutes part, the tests did not cover
+  the full range of valid inputs.
+
 ## v0.22.x - 2020-03
 
 * fix: workaround a libstdc++ bug on `std::random_device` (#208)

google/cloud/internal/parse_rfc3339.cc

@@ -94,7 +94,7 @@ std::chrono::system_clock::time_point ParseDateTime(
   if (hours < 0 || hours >= kHoursInDay) {
     ReportError(timestamp, "Out of range hour.");
   }
-  if (minutes < 0 || minutes >= kMinutesInHour - 1) {
+  if (minutes < 0 || minutes >= kMinutesInHour) {
     ReportError(timestamp, "Out of range minute.");
   }
   // RFC-3339 points out that the seconds field can only assume value '60' for

google/cloud/internal/parse_rfc3339_test.cc

@@ -45,10 +45,35 @@ TEST(ParseRfc3339Test, ParseEpoch) {
 }
 
 TEST(ParseRfc3339Test, ParseSimpleZulu) {
-  auto timestamp = ParseRfc3339("2018-05-18T14:42:03Z");
-  // Use `date -u +%s --date='2018-05-18T14:42:03'` to get the magic value:
-  EXPECT_EQ(1526654523L,
-            duration_cast<seconds>(timestamp.time_since_epoch()).count());
+  struct Timestamps {
+    std::string input;
+    std::time_t expected;
+  } tests[] = {
+      // Use `date -u +%s --date='....'` to get the expected values.
+      {"2018-05-18T14:42:03Z", 1526654523L},
+      {"2020-01-01T00:00:00Z", 1577836800L},
+      {"2020-01-31T00:00:00Z", 1580428800L},
+      {"2020-02-29T00:00:00Z", 1582934400L},
+      {"2020-03-31T00:00:00Z", 1585612800L},
+      {"2020-04-30T00:00:00Z", 1588204800L},
+      {"2020-05-31T00:00:00Z", 1590883200L},
+      {"2020-06-30T00:00:00Z", 1593475200L},
+      {"2020-07-31T00:00:00Z", 1596153600L},
+      {"2020-08-31T00:00:00Z", 1598832000L},
+      {"2020-09-30T00:00:00Z", 1601424000L},
+      {"2020-10-31T00:00:00Z", 1604102400L},
+      {"2020-11-20T00:00:00Z", 1605830400L},
+      {"2020-12-31T00:00:00Z", 1609372800L},
+      {"2020-01-01T00:00:59Z", 1577836859L},
+      {"2020-01-01T00:59:59Z", 1577840399L},
+      {"2020-01-01T23:59:59Z", 1577923199L},
+  };
+  for (auto const& test : tests) {
+    auto timestamp = ParseRfc3339(test.input);
+    auto actual = std::chrono::system_clock::to_time_t(timestamp);
+    EXPECT_EQ(actual, test.expected)
+        << " when testing with input=" << test.input;
+  }
 }
 
 TEST(ParseRfc3339Test, ParseAlternativeSeparators) {