move tests/language/std/date.nu -> modules/language/std/date.nu

- remove `main.nu`, there was only `source date.nu`
- adjust script for `playgroud/lib`

modules/language/tests/date.nu

@@ -0,0 +1,34 @@
+source ../playground/lib.nu
+source ../std/date.nu
+
+def mock-now [] {
+ "2021-08-29 03:31:21" | into datetime
+}
+
+def people [] {
+ [
+ [ 'name', 'tz'];
+ [ 'andres', 'America/Guayaquil']
+ [ 'fdncred', 'US/Central']
+ ]
+}
+
+playground "std/date" {
+
+ scene 'command: "date local"' {
+
+ play "adds times in local timezone" {|topic|
+
+ let expected_times = [
+ "Sun Aug 29 03:31:21 2021"
+ "Sun Aug 29 03:31:21 2021"
+ ] | into datetime;
+ let actual = (people | date local (mock-now) | get time | into datetime)
+
+ expect $topic $actual --to-be $expected_times
+
+ }
+
+ }
+
+}