clock.test: more tests for negative month offsets over threshold of a year (important for C-implementation like clock-speedup branch, see https://github.com/sebres/tclclockmod/issues/20#issuecomment-627704993)

1 files changed, 18 insertions, 0 deletions

diff --git a/tests/clock.test b/tests/clock.test
index 862e78c..f2edd34 100644
--- a/tests/clock.test
+++ b/tests/clock.test
@@ -35028,6 +35028,24 @@ test clock-30.8 {clock add months, negative} {
     set x4 [clock format $f4 -format %Y-%m-%d -timezone :UTC]
     list $x1 $x2 $x3 $x4
 } {2000-02-29 2000-01-31 1999-12-31 1999-11-30}
+test clock-30.8a {clock add months, negative, over threshold of a year} {
+    set t [clock scan 2019-01-31 -format %Y-%m-%d -gmt 1]
+    list [clock format [clock add $t -1 month -gmt 1] -format %Y-%m-%d -gmt 1] \
+	 [clock format [clock add $t -2 month -gmt 1] -format %Y-%m-%d -gmt 1] \
+	 [clock format [clock add $t -3 month -gmt 1] -format %Y-%m-%d -gmt 1] \
+	 [clock format [clock add $t -4 month -gmt 1] -format %Y-%m-%d -gmt 1]
+} {2018-12-31 2018-11-30 2018-10-31 2018-09-30}
+test clock-30.8b {clock add months, negative, over threshold of a year} {
+    set t [clock scan 2000-01-28 -format %Y-%m-%d -gmt 1]
+    for {set i 1} {$i < 24} {incr i 1} {
+	set f1 [clock add $t -$i month -gmt 1]
+	set f2 [clock add $f1 $i month -gmt 1]
+	if {$f2 != $t} {
+	    error "\[clock add $t -$i month -gmt 1\] does not consider\
+		   \[clock add $f1 $i month -gmt 1\] != $t"
+	}
+    }
+} {}
 test clock-30.9 {clock add days} {
     set t [clock scan {2000-01-01 12:34:56} -format {%Y-%m-%d %H:%M:%S} \
 	       -timezone :UTC]