StingType partition method failed to perform as expected with a space as the delimiter

Fortran matched the space with the empty string and failed to accurate partition the string

src/Strings.f90

@@ -349,7 +349,7 @@ PURE FUNCTION partition(this,sep) RESULT(tokens)
   TYPE(StringType) :: tokens(3)
   INTEGER(SIK) :: sepPos
   IF(ALLOCATED(this%s)) THEN
-    sepPos = MERGE(0,INDEX(this%s,sep),sep == '')
+    sepPos = MERGE(0,INDEX(this%s,sep),LEN(sep) == 0_SIK)
     IF(sepPos > 0) THEN
       tokens(1) = this%s(1:sepPos-1)
       tokens(3) = this%s(sepPos+LEN(SEP):LEN(this%s))
@@ -378,7 +378,7 @@ PURE FUNCTION rPartition(this,sep) RESULT(tokens)
   TYPE(StringType) :: tokens(3)
   INTEGER(SIK) :: sepPos
   IF(ALLOCATED(this%s)) THEN
-    sepPos = MERGE(0,INDEX(this%s,sep,.TRUE.),sep == '')
+    sepPos = MERGE(0,INDEX(this%s,sep,.TRUE.),LEN(sep) == 0_SIK)
     IF(sepPos > 0) THEN
       tokens(1) = this%s(1:sepPos-1)
       tokens(3) = this%s(sepPos+LEN(SEP):LEN(this%s))

unit_tests/testStrings/testStrings.f90

@@ -917,7 +917,20 @@ SUBROUTINE testStrFunct()
   ASSERT_EQ(CHAR(str_list(2)),'---','string with multiple delimter found')
   ASSERT_EQ(CHAR(str_list(3)),'','string with multiple delimter found')
 
+  str = 'abc def ghi'
+  str_list = str%partition(' ')
+  ASSERT_EQ(SIZE(str_list),3,'string with multiple delimter found')
+  ASSERT_EQ(CHAR(str_list(1)),'abc','string with multiple delimter found')
+  ASSERT_EQ(CHAR(str_list(2)),' ','string with multiple delimter found')
+  ASSERT_EQ(CHAR(str_list(3)),'def ghi','string with multiple delimter found')
+  str_list = str%rPartition(' ')
+  ASSERT_EQ(SIZE(str_list),3,'string with multiple delimter found')
+  ASSERT_EQ(CHAR(str_list(1)),'abc def','string with multiple delimter found')
+  ASSERT_EQ(CHAR(str_list(2)),' ','string with multiple delimter found')
+  ASSERT_EQ(CHAR(str_list(3)),'ghi','string with multiple delimter found')
+
 ENDSUBROUTINE testStrFunct
+!
 SUBROUTINE testConstructor
   TYPE(StringType) :: test0
   TYPE(StringType),ALLOCATABLE :: test1(:)