issue 5054

atest/robot/standard_libraries/builtin/should_contain.robot

@@ -27,6 +27,9 @@ Should Contain and do not collapse spaces
 Should Contain and collapse spaces
     Check Test Case    ${TESTNAME}
 
+Should Contain for bytes
+    Check Test Case    ${TESTNAME}
+
 Should Not Contain
     Check test case    ${TESTNAME}
 

atest/testdata/standard_libraries/builtin/should_contain.robot

@@ -100,6 +100,12 @@ Should Contain and collapse spaces
     ${LIST4}      \tb\n     collapse_spaces=TRUE
     ${LIST4}      \tc\n     collapse_spaces=TRUE
 
+Should Contain for bytes
+    [Documentation]     FAIL ValueError: byte must be in range(0, 256)
+    [Template]    Should Contain
+    ${BINARY}    \xA0
+    ${BINARY}    ${1000}
+
 Should Not Contain
     [Documentation]    FAIL 'Hello yet again' contains 'yet'
     [Template]    Should Not Contain

atest/testdata/standard_libraries/builtin/variables_to_verify.py

@@ -23,7 +23,8 @@ def get_variables():
         DICT_3={'a': 1, 'b': 2, 'c': 3},
         DICT_4={'\ta': 1, 'a b': 2, '  c': 3, 'dd\n\t': 4, '\nak \t': 5},
         DICT_5={' a': 0, '\ta': 1, 'a\t': 2, '\nb': 3, 'd\t': 4, '\td\n': 5, 'e   e': 6},
-        PREPR_DICT1="{'a': 1}"
+        PREPR_DICT1="{'a': 1}",
+        BINARY=b'\x00\x01\x02\xA0\xB0'
     )
     variables['ASCII_DICT'] = ascii(variables['DICT'])
     return variables

src/robot/libraries/BuiltIn.py

@@ -1072,6 +1072,11 @@ def should_contain(self, container, item, msg=None, values=True,
         in Robot Framework 4.1.
         """
         orig_container = container
+        if isinstance(container, bytes) and isinstance(item, str):
+            try:
+                item = item.encode('latin-1')
+            except UnicodeEncodeError:
+                raise ValueError("{item} can not be encoded into bytes.")
         if ignore_case and is_string(item):
             item = item.casefold()
             if is_string(container):