added fail messages and put fullstop (.) in documentation

Author: aman-godara

doc/specs/stdlib_strings.md

@@ -233,13 +233,13 @@ Pure function.
 
 #### Argument
 
-- `string`: Character scalar or [[stdlib_string_type(module):string_type(type)]]
+- `string`: Character scalar or [[stdlib_string_type(module):string_type(type)]].
   This argument is intent(in).
-- `first`: integer
+- `first`: integer.
   This argument is intent(in) and optional.
-- `last`: integer
+- `last`: integer.
   This argument is intent(in) and optional.
-- `stride`: integer
+- `stride`: integer.
   This argument is intent(in) and optional.
 
 #### Result value
@@ -298,13 +298,13 @@ Pure function
 
 #### Argument
 
-- `string`: Character scalar or [[stdlib_string_type(module):string_type(type)]]
+- `string`: Character scalar or [[stdlib_string_type(module):string_type(type)]].
   This argument is intent(in).
-- `pattern`: Character scalar or [[stdlib_string_type(module):string_type(type)]]
+- `pattern`: Character scalar or [[stdlib_string_type(module):string_type(type)]].
   This argument is intent(in).
-- `occurrence`: integer
+- `occurrence`: integer.
   This argument is intent(in) and optional.
-- `consider_overlapping`: logical
+- `consider_overlapping`: logical.
   This argument is intent(in) and optional.
 
 #### Result value

src/tests/string/test_string_functions.f90

@@ -166,15 +166,24 @@ subroutine test_find
         type(string_type) :: test_string, test_pattern
         test_string = "qwqwqwqwqwqwqw"
         test_pattern = "qwq"
-        call check(find(test_string, test_pattern, 4) == 7)
-        call check(find(test_string, test_pattern, 3, .false.) == 9)
-        call check(find(test_string, test_pattern, 7) == 0)
-        call check(find("qwqwqwqwqwqwqw", test_pattern) == 1)
-        call check(find(test_string, "qwq", 2) == 3)
-        call check(find("qwqwqwqwqwqwqw", "qwq", 2, .false.) == 5)
-        call check(find("", "") == 0)
-        call check(find("", test_pattern) == 0)
-        call check(find(test_string, "") == 0)
+        call check(find(test_string, test_pattern, 4) == 7, &
+            & 'Find: test_string, test_pattern, 4')
+        call check(find(test_string, test_pattern, 3, .false.) == 9, &
+            & 'Find: test_string, test_pattern, 3')
+        call check(find(test_string, test_pattern, 7) == 0, &
+            & 'Find: test_string, test_pattern, 7')
+        call check(find("qwqwqwqwqwqwqw", test_pattern) == 1, &
+            & 'Find: "qwqwqwqwqwqwqw", test_pattern')
+        call check(find(test_string, "qwq", 2) == 3, &
+            &, 'Find: test_string, "qwq", 2')
+        call check(find("qwqwqwqwqwqwqw", "qwq", 2, .false.) == 5, &
+            & 'Find: "qwqwqwqwqwqwqw", "qwq", 2, .false.')
+        call check(find("", "") == 0, &
+            & 'Find: "", ""')
+        call check(find("", test_pattern) == 0, &
+            & 'Find: "", test_pattern')
+        call check(find(test_string, "") == 0, &
+            &, 'Find: test_string, ""')
 
     end subroutine test_find