Clarify and fix TZ stuff in (datetime).

1 files changed, 49 insertions, 0 deletions

diff --git a/tests/tz.scm b/tests/tz.scm
new file mode 100644
index 00000000..321bb960
--- /dev/null
+++ b/tests/tz.scm
@@ -0,0 +1,49 @@
+(((datetime)
+  parse-ics-datetime
+  datetime date time
+  datetime->unix-time
+  unix-time->datetime
+  get-datetime)
+ ((util) let-env))
+
+;; London alternates between +0000 and +0100
+(let-env ((TZ "Europe/London"))
+ (test-equal "London winter"
+   #2020-01-12T13:30:00
+   (get-datetime (parse-ics-datetime "20200112T133000Z")))
+ (test-equal "London summer"
+   #2020-06-12T14:30:00
+   (get-datetime (parse-ics-datetime "20200612T133000Z"))))
+
+;; Stockholm alternates between +0100 and +0200
+(let-env ((TZ "Europe/Stockholm"))
+ (test-equal "Stockholm winter"
+   #2020-01-12T14:30:00
+   (get-datetime (parse-ics-datetime "20200112T133000Z")))
+ (test-equal "Stockholm summer"
+   #2020-06-12T15:30:00
+   (get-datetime (parse-ics-datetime "20200612T133000Z"))) )
+
+(test-equal
+    -10800
+  (datetime->unix-time
+   (parse-ics-datetime "19700101T000000" "Europe/Tallinn")))
+
+(test-equal
+    -3600
+  (datetime->unix-time
+   (parse-ics-datetime "19700101T000000" "Europe/Stockholm")))
+
+(test-equal
+    0
+  (datetime->unix-time (parse-ics-datetime "19700101T000000Z")))
+
+;; yes, really
+(test-equal
+    -3600
+  (datetime->unix-time
+   (parse-ics-datetime "19700101T000000" "Europe/London")))
+
+(test-equal
+    #1970-01-01T00:00:00Z
+  (unix-time->datetime 0))