pytest.fail: fix ANSI escape codes for colored output (#12959)

- When `ReprEntry.style == "value"` (happens when calling `pytest.fail(..., pytrace=False)`, the message should not be printed to terminal using `TerminalWriter._write_source` because then it'll try to highlight the message as source code
- The message should be printed to terminal directly using `TerminalWriter.line` or `TerminalWriter.write`, I went with the later for testing purposes https://github.com/pytest-dev/pytest/pull/12959#discussion_r1842574618

Closes #12849

AUTHORS

@@ -247,6 +247,7 @@ Kristoffer Nordström
 Kyle Altendorf
 Lawrence Mitchell
 Lee Kamentsky
+Leonardus Chen
 Lev Maximov
 Levon Saldamli
 Lewis Cowles

changelog/12849.bugfix.rst

@@ -0,0 +1 @@
+ANSI escape codes for colored output now handled correctly in :func:`pytest.fail` with `pytrace=False`.

src/_pytest/_code/code.py

@@ -1221,6 +1221,15 @@ class ReprEntry(TerminalRepr):
         if not self.lines:
             return
 
+        if self.style == "value":
+            # Using tw.write instead of tw.line for testing purposes due to TWMock implementation;
+            # lines written with TWMock.line and TWMock._write_source cannot be distinguished
+            # from each other, whereas lines written with TWMock.write are marked with TWMock.WRITE
+            for line in self.lines:
+                tw.write(line)
+                tw.write("\n")
+            return
+
         # separate indents and source lines that are not failures: we want to
         # highlight the code but not the indentation, which may contain markers
         # such as ">   assert 0"
@@ -1236,11 +1245,8 @@ class ReprEntry(TerminalRepr):
                 failure_lines.extend(self.lines[index:])
                 break
             else:
-                if self.style == "value":
-                    source_lines.append(line)
-                else:
-                    indents.append(line[:indent_size])
-                    source_lines.append(line[indent_size:])
+                indents.append(line[:indent_size])
+                source_lines.append(line[indent_size:])
 
         tw._write_source(source_lines, indents)
 

testing/code/test_excinfo.py

@@ -1194,6 +1194,23 @@ raise ValueError()
         line = tw_mock.lines[-1]
         assert line == ":3: ValueError"
 
+    def test_toterminal_value(self, importasmod, tw_mock):
+        mod = importasmod(
+            """
+            def g(x):
+                raise ValueError(x)
+            def f():
+                g('some_value')
+        """
+        )
+        excinfo = pytest.raises(ValueError, mod.f)
+        excinfo.traceback = excinfo.traceback.filter(excinfo)
+        repr = excinfo.getrepr(style="value")
+        repr.toterminal(tw_mock)
+
+        assert tw_mock.get_write_msg(0) == "some_value"
+        assert tw_mock.get_write_msg(1) == "\n"
+
     @pytest.mark.parametrize(
         "reproptions",
         [

testing/conftest.py

@@ -119,8 +119,8 @@ def tw_mock():
             return text
 
         def get_write_msg(self, idx):
-            flag, msg = self.lines[idx]
-            assert flag == TWMock.WRITE
+            assert self.lines[idx][0] == TWMock.WRITE
+            msg = self.lines[idx][1]
             return msg
 
         fullwidth = 80