Fixes for invalid GMT offset when creating new DateTimeZone in post-edit widget

[benlk]

Changes

• Where the plugin generates a DateTimeZone object from the database, moves that construction into its own separate testable function nprstory_get_datetime()
• Includes a test for said function that iterates over the known valid GMT offsets from WordPress's database. This doesn't cover all possible GMT offsets, of which there are a ton. This covers almost every offset seen in WordPress's selector drop-down, and a few 45-minute-off timezones. It does not cover the 20- and 40-minute-off time zones. It does cover the '' empty-string option_value of 'gmt_offset', which is what this plugin was tested under in the first place.

Notes

• This does not need to check the option_value 'timezone_string' because WordPress uses that value in the function wp_timezone_override_offset which is a filter upon the output of get_option( 'gmt_offset' );

Why

#52 is described based on an email from Erin, and is caused by DateTimeZone::__construct() not accepting GMT offsets in the format that WordPress saves them in the database. WordPress saves them as decimal hours; PHP's DateTimeZone::__construct() seems to want the offset in seconds. I say "seems" because it's not explicitly described as such in any php.net documentation, but the documentation for DateTimeZone::listAbbreviations() and the output of that function both describe offsets in numbers that only make sense as whole hours if the number displayed is a number of hours multiplied by 360.

As a sample:

[0] => Array
        (
            [dst] => 1
            [offset] => -14400
            [timezone_id] => America/Porto_Acre
        )

The time zone "America/Porto_Acre" has an offset -14400. -14400 divided by powers of ten doesn't seem correct. -14400 divided by 60 is -240; divided by 60*60=360 is -4. Checking https://en.wikipedia.org/wiki/List_of_tz_database_time_zones shows that the offset for "America/Porto_Acre" is presently -05:00. The one-hour discrepancy between -4 and -05:00 is explained by "America/Porto_Acre" being subject to daylight saving time.

Fixes #52.

[benlk]

Automated tests pass.

Human-run tests should perform the following tasks:

1. Activate the plugin
2. Configure the plugin with test API credentials
3. Create a new post.
   1. Does the NPR Story API meta box appear on the page?
   2. Are there no errors in the server console?
   3. Change the time zone in Dashboard > Settings > General to a new time zone. Repeat step 3 until satisfied.
4. Push a post to the API.
5. Pull a post from the API.

[ghost]

Code looks good to me

[eteare]

I have uploaded the master repo to our test WP site. I made posts and changed dates, but I am unable to get stories to or pull stories from the API. There could be some operator error here, however, when I tried to pull just one story, I got this error message.

Do you think this error is related to plugin updates or something in our WP site's config? Any insights helpful. Thank you.

[benlk]

There's two issues there:

"non-static method DS_NPR_API::load_page_hook() should not be called statically" — this should not prevent the page from loading.

"call to undefined function simplexml_load_string()" — this has me puzzled, because that function appears to be a standard part of PHP. Was your test server's PHP compiled without the SimpleXML extension? https://secure.php.net/manual/en/simplexml.setup.php