From fbdb04dcbe1ab4da2aa446c572f89ff41ec85a9c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ferm=C3=ADn=20Gal=C3=A1n=20M=C3=A1rquez?=
 <fermin.galanmarquez@telefonica.com>
Date: Wed, 6 Mar 2024 09:53:20 +0100
Subject: [PATCH] ADD section about simulated time to documentation

---
 README.md | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/README.md b/README.md
index f3d87a7..4f5c121 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,30 @@ Result:
 a text string
 ```
 
+## Using simulated time
+
+By default, the current time reference used by [date related transformations](#date related transformations) is system current time. However, this can be changed using the positional argument `now` in the `JEXL` constructor to specify a function that returns a `datetime` object to be used as current time.
+
+For instance, if we want to set current time to November 13th, 2020 at 6:24:58am we can use:
+
+```python
+from tcjexl import JEXL
+import datetime
+
+def simulated_time():
+    return datetime.datetime(2020, 11, 13, 6, 24, 58, 000, tzinfo=datetime.timezone.utc)
+
+jexl = JEXL(now=simulated_time)
+
+print(jexl.evaluate('0|currentTimeIso', {}))
+```
+
+Result:
+
+```
+2020-11-13T06:24:58.000Z
+```
+
 ## Included transformations
 
 **NOTE:** JEXL pipeline is needed even if the transformation doesn't need an parameter to work (e.g. `currentTime` that provides the current system time and doesn't need and argument). In this case, we use `0|` for these cases (e.g. `0|currentTime`).