Raise useful error if trying to use RichTracebackFormatter w/o Rich

CHANGELOG.md

@@ -27,6 +27,12 @@ You can find our backwards-compatibility policy [here](https://github.com/hynek/
   [#717](https://github.com/hynek/structlog/pull/717)
 
 
+### Changed
+
+- `structlog.dev.rich_traceback()` now throws a more helpful error when Rich is missing.
+  [#735](https://github.com/hynek/structlog/pull/735)
+
+
 ## [25.4.0](https://github.com/hynek/structlog/compare/25.3.0...25.4.0) - 2025-06-02
 
 ### Added

src/structlog/dev.py

@@ -412,17 +412,26 @@ def __call__(self, sio: TextIO, exc_info: ExcInfo) -> None:
         console.print(tb)
 
 
-rich_traceback = RichTracebackFormatter()
-"""
-Pretty-print *exc_info* to *sio* using the Rich package.
+if rich is None:
 
-To be passed into `ConsoleRenderer`'s ``exception_formatter`` argument.
+    def rich_traceback(*args, **kw):
+        raise ModuleNotFoundError(
+            "RichTracebackFormatter requires Rich to be installed.",
+            name="rich",
+        )
 
-This is a `RichTracebackFormatter` with default arguments and used by default
-if Rich is installed.
+else:
+    rich_traceback = RichTracebackFormatter()
+    """
+    Pretty-print *exc_info* to *sio* using the Rich package.
 
-.. versionadded:: 21.2.0
-"""
+    To be passed into `ConsoleRenderer`'s ``exception_formatter`` argument.
+
+    This is a `RichTracebackFormatter` with default arguments and used by default
+    if Rich is installed.
+
+    .. versionadded:: 21.2.0
+    """
 
 
 def better_traceback(sio: TextIO, exc_info: ExcInfo) -> None:

tests/test_dev.py

@@ -649,6 +649,19 @@ def test_set_it(self):
         assert {"exc_info": True} == dev.set_exc_info(None, "exception", {})
 
 
+@pytest.mark.skipif(dev.rich is not None, reason="Needs missing Rich.")
+def test_rich_traceback_formatter_no_rich():
+    """
+    Trying to use RichTracebackFormatter without Rich should raise an helpful
+    error.
+    """
+    with pytest.raises(
+        ModuleNotFoundError,
+        match="RichTracebackFormatter requires Rich to be installed.",
+    ):
+        dev.rich_traceback(StringIO(), sys.exc_info())
+
+
 @pytest.mark.skipif(dev.rich is None, reason="Needs Rich.")
 class TestRichTracebackFormatter:
     def test_default(self):