BuiltIn: Fix multiline error message with custom messages.

pekkaklarck · pekkaklarck · commit af92ca7269cf · 2021-10-14T18:46:07.000+03:00
Fixes #4116.
diff --git a/atest/robot/standard_libraries/builtin/should_be_equal.robot b/atest/robot/standard_libraries/builtin/should_be_equal.robot
@@ -39,6 +39,10 @@ Multiline comparison uses diff
     ${tc} =    Check test case    ${TESTNAME}
     Check Log Message    ${tc.kws[0].msgs[1]}    foo\nbar\ndar\n\n!=\n\nfoo\nbar\ngar\n\ndar
 
+Multiline comparison with custom message
+    ${tc} =    Check test case    ${TESTNAME}
+    Check Log Message    ${tc.kws[0].msgs[1]}    foo\nbar\ndar\n\n!=\n\nfoo\nbar\ngar\n\ndar
+
 Multiline comparison requires both multiline
     Check test case    ${TESTNAME}
 
diff --git a/atest/robot/standard_libraries/builtin/should_be_equal_as_xxx.robot b/atest/robot/standard_libraries/builtin/should_be_equal_as_xxx.robot
@@ -62,6 +62,9 @@ Should Be Equal As Strings repr
 Should Be Equal As Strings multiline
     Check test case    ${TESTNAME}
 
+Should Be Equal As Strings multiline with custom message
+    Check test case    ${TESTNAME}
+
 Should Be Equal As Strings repr multiline
     Check test case    ${TESTNAME}
 
diff --git a/atest/testdata/standard_libraries/builtin/should_be_equal.robot b/atest/testdata/standard_libraries/builtin/should_be_equal.robot
@@ -94,6 +94,20 @@ Multiline comparison uses diff
     ...    +
     foo\nbar\ndar\n    foo\nbar\ngar\n\ndar\n\n
 
+Multiline comparison with custom message
+    [Documentation]    FAIL
+    ...    Custom message of mine: Multiline strings are different:
+    ...    --- first
+    ...    +++ second
+    ...    @@ -1,3 +1,6 @@
+    ...    \ foo
+    ...    \ bar
+    ...    +gar
+    ...    +
+    ...    \ dar
+    ...    +
+    foo\nbar\ndar\n    foo\nbar\ngar\n\ndar\n\n    msg=Custom message of mine
+
 Multiline comparison requires both multiline
     [Documentation]    FAIL foo\nbar\ndar != foobar
     foo\nbar\ndar    foobar
diff --git a/atest/testdata/standard_libraries/builtin/should_be_equal_as_xxx.robot b/atest/testdata/standard_libraries/builtin/should_be_equal_as_xxx.robot
@@ -153,6 +153,20 @@ Should Be Equal As Strings multiline
     ...   \ dar
     Should Be Equal As Strings    foo\nbar\r\ndar    foo\nbar\ngar\ndar
 
+Should Be Equal As Strings multiline with custom message
+    [Documentation]    FAIL
+    ...    Custom message of mine: Multiline strings are different:
+    ...    --- first
+    ...    +++ second
+    ...    @@ -1,3 +1,4 @@
+    ...   \ foo
+    ...    -bar
+    ...    +bar
+    ...    +gar
+    ...   \ dar
+    Should Be Equal As Strings    foo\nbar\r\ndar    foo\nbar\ngar\ndar
+    ...    msg=Custom message of mine
+
 Should Be Equal As Strings repr multiline
     [Documentation]    FAIL
     ...    Multiline strings are different:
diff --git a/src/robot/libraries/BuiltIn.py b/src/robot/libraries/BuiltIn.py
@@ -657,14 +657,14 @@ def _should_be_equal(self, first, second, msg, values, formatter='str'):
         if first == second:
             return
         if include_values and is_string(first) and is_string(second):
-            self._raise_multi_diff(first, second, formatter)
+            self._raise_multi_diff(first, second, msg, formatter)
         assert_equal(first, second, msg, include_values, formatter)
 
     def _log_types_at_info_if_different(self, first, second):
         level = 'DEBUG' if type(first) == type(second) else 'INFO'
         self._log_types_at_level(level, first, second)
 
-    def _raise_multi_diff(self, first, second, formatter):
+    def _raise_multi_diff(self, first, second, msg, formatter):
         first_lines = first.splitlines(True)      # keepends
         second_lines = second.splitlines(True)
         if len(first_lines) < 3 or len(second_lines) < 3:
@@ -673,10 +673,11 @@ def _raise_multi_diff(self, first, second, formatter):
         diffs = list(difflib.unified_diff(first_lines, second_lines,
                                           fromfile='first', tofile='second',
                                           lineterm=''))
-        diffs[3:] = [item[0] + formatter(item[1:]).rstrip()
-                     for item in diffs[3:]]
-        raise AssertionError('Multiline strings are different:\n' +
-                             '\n'.join(diffs))
+        diffs[3:] = [item[0] + formatter(item[1:]).rstrip() for item in diffs[3:]]
+        prefix = 'Multiline strings are different:'
+        if msg:
+            prefix = '%s: %s' % (msg, prefix)
+        raise AssertionError('\n'.join([prefix] + diffs))
 
     def _include_values(self, values):
         return is_truthy(values) and str(values).upper() != 'NO VALUES'
