From 1ef1fc269e2b682a2d8053340e8349436a132269 Mon Sep 17 00:00:00 2001
From: Timothy Pogue <me@pogue.dev>
Date: Wed, 7 Sep 2022 15:26:38 -0600
Subject: [PATCH] docstring and tests

---
 freqtrade/strategy/strategy_helper.py   |  4 +++-
 tests/strategy/test_strategy_helpers.py | 23 +++++++++++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/freqtrade/strategy/strategy_helper.py b/freqtrade/strategy/strategy_helper.py
index 55afbf7a8..53f625001 100644
--- a/freqtrade/strategy/strategy_helper.py
+++ b/freqtrade/strategy/strategy_helper.py
@@ -31,6 +31,8 @@ def merge_informative_pair(dataframe: pd.DataFrame, informative: pd.DataFrame,
     :param ffill: Forwardfill missing values - optional but usually required
     :param append_timeframe: Rename columns by appending timeframe.
     :param date_column: A custom date column name.
+    :param suffix: A string suffix to add at the end of the informative columns. If specified,
+                   append_timeframe must be false.
     :return: Merged dataframe
     :raise: ValueError if the secondary timeframe is shorter than the dataframe timeframe
     """
@@ -57,7 +59,7 @@ def merge_informative_pair(dataframe: pd.DataFrame, informative: pd.DataFrame,
         date_merge = f'date_merge_{timeframe_inf}'
         informative.columns = [f"{col}_{timeframe_inf}" for col in informative.columns]
 
-    elif suffix:
+    elif suffix and not append_timeframe:
         date_merge = f'date_merge_{suffix}'
         informative.columns = [f"{col}_{suffix}" for col in informative.columns]
 
diff --git a/tests/strategy/test_strategy_helpers.py b/tests/strategy/test_strategy_helpers.py
index a7c2da26a..8cb990e87 100644
--- a/tests/strategy/test_strategy_helpers.py
+++ b/tests/strategy/test_strategy_helpers.py
@@ -117,6 +117,29 @@ def test_merge_informative_pair_lower():
         merge_informative_pair(data, informative, '1h', '15m', ffill=True)
 
 
+def test_merge_informative_pair_suffix():
+    data = generate_test_data('15m', 20)
+    informative = generate_test_data('1h', 20)
+
+    result = merge_informative_pair(data, informative, '15m', '1h',
+                                    append_timeframe=False, suffix="suf")
+
+    assert 'date' in result.columns
+    assert result['date'].equals(data['date'])
+    assert 'date_suf' in result.columns
+
+    assert 'open_suf' in result.columns
+    assert 'open_1h' not in result.columns
+
+
+def test_merge_informative_pair_suffix_append_timeframe():
+    data = generate_test_data('15m', 20)
+    informative = generate_test_data('1h', 20)
+
+    with pytest.raises(ValueError, match=r"You can not specify `append_timeframe` .*"):
+        merge_informative_pair(data, informative, '15m', '1h', suffix="suf")
+
+
 def test_stoploss_from_open():
     open_price_ranges = [
         [0.01, 1.00, 30],