Add validate test for timezones

test/tz_test/README.md

@@ -0,0 +1,28 @@
+To test: * Install tz.cpp by downloading the IANA timezone database
+at: http://www.iana.org/time-zones You only need the data, not the
+code.
+
+* Change the string `install` in tz.cpp to point to your downloaded
+IANA database.
+
+* Compile validate.cpp along with tz.cpp.
+
+* Run the binary and direct the terminal output to a temporary file.
+
+* Unzip the tzdata file that has the version corresponding to the IANA
+database you downloaded (e.g. tzdata2015f.txt.zip).
+
+* Compare the unzipped txt file with the output of your validate test
+program. If they are identical, the test passes, else it fails.
+
+Miscellaneous:
+
+You can also compare one version of the tzdatabase with another using
+these uncompressed text files.  The text files contain for each
+timezone its initial state, and each {offset, abbreviation} change
+contained in the database up through the year 2035.  As the database
+versions change, minor updates to the set of these transitions are
+typically made, typically due to changes in government policies.
+
+The tests in this section will run much faster with optimizations
+cranked up.

test/tz_test/validate.cpp

@@ -0,0 +1,60 @@
+#include "tz.h"
+#include <iostream>
+
+int
+main()
+{
+    using namespace date;
+    using namespace std::chrono;
+    auto& db = get_tzdb();
+    std::vector<std::string> names;
+    names.reserve(db.zones.size() + db.links.size());
+    for (auto& zone : db.zones)
+        names.push_back(zone.name());
+    for (auto& link : db.links)
+        names.push_back(link.name());
+    std::sort(names.begin(), names.end());
+    for (auto const& name : names)
+    {
+        std::cout << name << '\n';
+        auto z = locate_zone(name);
+        auto begin = day_point(jan/1/year::min()) + 0s;
+        auto end   = day_point(jan/1/2035) + 0s;
+        auto info = z->get_info(begin, tz::utc);
+        std::cout << "Initially:           ";
+        if (info.offset >= 0s)
+            std::cout << '+';
+        std::cout << make_time(info.offset);
+        if (info.save == 0min)
+            std::cout << " standard ";
+        else
+            std::cout << " daylight ";
+        std::cout << info.abbrev << '\n';
+        auto prev_offset = info.offset;
+        auto prev_abbrev = info.abbrev;
+        auto prev_save = info.save;
+        for (begin = info.end; begin < end; begin = info.end)
+        {
+            info = z->get_info(begin, tz::utc);
+            if (info.offset == prev_offset && info.abbrev == prev_abbrev &&
+                    info.save == prev_save)
+                continue;
+            auto dp = floor<days>(begin);
+            auto ymd = year_month_day(dp);
+            auto time = make_time(begin - dp);
+            std::cout << ymd << 'T' << time << "Z ";
+            if (info.offset >= 0s)
+                std::cout << '+';
+            std::cout << make_time(info.offset);
+            if (info.save == 0min)
+                std::cout << " standard ";
+            else
+                std::cout << " daylight ";
+            std::cout << info.abbrev << '\n';
+            prev_offset = info.offset;
+            prev_abbrev = info.abbrev;
+            prev_save = info.save;
+        }
+        std::cout << '\n';
+    }
+}

tz.cpp

@@ -113,7 +113,7 @@ namespace date
 #if _WIN32 // TODO: sensible default for all platforms.
 static std::string install{ "c:\\tzdata" };
 #else
-static std::string install{ "/Users/howardhinnant/Downloads/tzdata2015e" };
+static std::string install{ "/Users/howardhinnant/Downloads/tzdata2015f" };
 #endif
 
 static const std::vector<std::string> files =