Adde some tests for string/format

test/suite4.janet

@@ -0,0 +1,34 @@
+# Copyright (c) 2019 Calvin Rose
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to
+# deal in the Software without restriction, including without limitation the
+# rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+# sell copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+# IN THE SOFTWARE.
+
+(import test/helper :prefix "" :exit true)
+(start-suite 4)
+# some tests for string/format
+
+(assert (= (string (string/format @"" "pi = %6.3f" math/pi)) "pi =  3.142") "%6.3f")
+(assert (= (string (string/format @"" "pi = %+6.3f" math/pi)) "pi = +3.142") "%6.3f")
+(assert (= (string (string/format @"" "pi = %40.20g" math/pi)) "pi =                     3.141592653589793116") "%6.3f")
+
+(assert (= (string (string/format @"" "🐼 = %6.3f" math/pi)) "🐼 =  3.142") "UTF-8")
+(assert (= (string (string/format @"" "π = %.8g" math/pi)) "π = 3.1415927") "π")
+(assert (= (string (string/format @"" "\xCF\x80 = %.8g" math/pi)) "\xCF\x80 = 3.1415927") "\xCF\x80")
+
+(end-suite)
+