From f692d96008b835f442e118e5b77a462a96614ba2 Mon Sep 17 00:00:00 2001
From: Jakob Schnitzer <mail@jakobschnitzer.de>
Date: Sun, 15 Sep 2024 17:49:32 +0200
Subject: [PATCH] add some tests for entries.update_postings

---
 smart_importer/entries.py | 26 ++++++++++++++------
 tests/entries_test.py     | 50 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 7 deletions(-)
 create mode 100644 tests/entries_test.py

diff --git a/smart_importer/entries.py b/smart_importer/entries.py
index c336550..b05e1d2 100644
--- a/smart_importer/entries.py
+++ b/smart_importer/entries.py
@@ -1,22 +1,34 @@
 """Helpers to work with Beancount entry objects."""
 
+from __future__ import annotations
+
 from beancount.core.data import Posting, Transaction
 
 
-def update_postings(transaction, accounts):
-    """Update the list of postings of a transaction to match the accounts."""
+def update_postings(
+    transaction: Transaction, accounts: list[str]
+) -> Transaction:
+    """Update the list of postings of a transaction to match the accounts.
+
+    Expects the transaction to be updated to have exactly one posting,
+    otherwise it is returned unchanged. Adds empty postings for all the
+    accounts - if the account of the single existing posting is found
+    in the list of accounts, it is placed there at the first occurence,
+    otherwise it is appended at the end.
+    """
 
     if len(transaction.postings) != 1:
         return transaction
 
+    posting = transaction.postings[0]
+
     new_postings = [
         Posting(account, None, None, None, None, None) for account in accounts
     ]
-    for posting in transaction.postings:
-        if posting.account in accounts:
-            new_postings[accounts.index(posting.account)] = posting
-        else:
-            new_postings.append(posting)
+    if posting.account in accounts:
+        new_postings[accounts.index(posting.account)] = posting
+    else:
+        new_postings.append(posting)
 
     return transaction._replace(postings=new_postings)
 
diff --git a/tests/entries_test.py b/tests/entries_test.py
new file mode 100644
index 0000000..cc29de9
--- /dev/null
+++ b/tests/entries_test.py
@@ -0,0 +1,50 @@
+"""Tests for the entry helpers."""
+
+from __future__ import annotations
+
+# pylint: disable=missing-docstring
+from beancount.parser import parser
+
+from smart_importer.entries import update_postings
+
+TEST_DATA, _errors, _options = parser.parse_string(
+    """
+2016-01-06 * "Farmer Fresh" "Buying groceries"
+  Assets:US:BofA:Checking  -10.00 USD
+
+2016-01-06 * "Farmer Fresh" "Buying groceries"
+  Assets:US:BofA:Checking  -10.00 USD
+  Assets:US:BofA:Checking   10.00 USD
+"""
+)
+
+
+def test_update_postings() -> None:
+    txn0 = TEST_DATA[0]
+
+    def _update(accounts: list[str]) -> list[tuple[str, bool]]:
+        """Update, get accounts and whether this is the original posting."""
+        updated = update_postings(txn0, accounts)
+        return [(p.account, p is txn0.postings[0]) for p in updated.postings]
+
+    assert _update(["Assets:US:BofA:Checking", "Assets:Other"]) == [
+        ("Assets:US:BofA:Checking", True),
+        ("Assets:Other", False),
+    ]
+
+    assert _update(
+        ["Assets:US:BofA:Checking", "Assets:US:BofA:Checking", "Assets:Other"]
+    ) == [
+        ("Assets:US:BofA:Checking", True),
+        ("Assets:US:BofA:Checking", False),
+        ("Assets:Other", False),
+    ]
+
+    assert _update(["Assets:Other", "Assets:Other2"]) == [
+        ("Assets:Other", False),
+        ("Assets:Other2", False),
+        ("Assets:US:BofA:Checking", True),
+    ]
+
+    txn1 = TEST_DATA[1]
+    assert update_postings(txn1, ["Assets:Other"]) == txn1