Add note to readme and a test case

README.md

@@ -510,6 +510,13 @@ defaultChroniclesStream.output.writer =
     database.writeLogEntry(msg)
 ```
 
+## Using Chronicles with `{.noSideEffect.}`
+
+Usage of Chronicles from `noSideEffect` procs (or `func`) is limited to the
+`trace` statement. Normal logging can be considered a side effect, but `trace`
+is meant as a debugging aid. It's analogous to Nim's `debugEcho`, which also
+bypasses the effect system.
+
 ## Teaching Chronicles about your types
 
 Chronicles can output log records in any of the formats supported by the Nim

tests/loglevel/trace_level.test

@@ -0,0 +1,9 @@
+program=no_side_effect
+chronicles_sinks="textlines[stdout]"
+chronicles_colors=None
+chronicles_timestamps=None
+chronicles_log_level=TRACE
+
+[Output]
+stdout="""TRC effect-free                                tid=0
+"""

tests/no_side_effect.nim

@@ -0,0 +1,6 @@
+import chronicles
+
+func main =
+  trace "effect-free"
+
+main()