feat(test_description): make contains_text generic

This commit makes the test_description_t type's "contains_text"
binding generic with two corresponding specific (private)
type-bound functions: contains_string_t and the new
contains_characters.

src/julienne/julienne_test_description_m.f90

@@ -24,9 +24,10 @@ function test_function_i() result(passes)
     procedure(test_function_i), pointer, nopass :: test_function_ => null()
   contains
     procedure run
-    procedure contains_text
+    generic :: contains_text => contains_string_t, contains_characters
+    procedure, private ::       contains_string_t, contains_characters
     generic :: operator(==) => equals
-    procedure, private :: equals
+    procedure, private ::      equals
   end type
 
   interface test_description_t
@@ -58,14 +59,22 @@ impure elemental module function run(self) result(test_result)
       type(test_result_t) test_result
     end function
 
-    impure elemental module function contains_text(self, substring) result(match)
-      !! The result is .true. if the test description includes the value of substring 
+    impure elemental module function contains_string_t(self, substring) result(match)
+      !! The result is .true. if the test description includes the value of substring
       implicit none
       class(test_description_t), intent(in) :: self
       type(string_t), intent(in) :: substring
       logical match
     end function
 
+    impure elemental module function contains_characters(self, substring) result(match)
+      !! The result is .true. if the test description includes the value of substring
+      implicit none
+      class(test_description_t), intent(in) :: self
+      character(len=*), intent(in) :: substring
+      logical match
+    end function
+
     elemental module function equals(lhs, rhs) result(lhs_eq_rhs)
       !! The result is .true. if the components of the lhs & rhs are equal
       implicit none

src/julienne/julienne_test_description_s.f90

@@ -17,10 +17,14 @@
       test_result = test_result_t(self%description_, self%test_function_())
     end procedure
 
-    module procedure contains_text
+    module procedure contains_string_t
       match = index(self%description_%string(), substring%string()) /= 0
     end procedure
 
+    module procedure contains_characters
+      match = index(self%description_%string(), substring) /= 0
+    end procedure
+
     module procedure equals
       lhs_eq_rhs = (lhs%description_ == rhs%description_) .and. associated(lhs%test_function_, rhs%test_function_)
     end procedure