From 543df7c1d43c49fd8cf48e7028524cb760da5654 Mon Sep 17 00:00:00 2001
From: Baptiste Jonglez <git@bitsofnetworks.org>
Date: Tue, 3 Jan 2017 21:36:49 +0100
Subject: [PATCH 1/3] Add a test to catch zero-amount transfers in the settle
 page

---
 budget/tests.py | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/budget/tests.py b/budget/tests.py
index eea7537..f0a5ea7 100644
--- a/budget/tests.py
+++ b/budget/tests.py
@@ -580,6 +580,46 @@ class BudgetTestCase(TestCase):
             self.assertEqual(a, balance[m.id])
         return
 
+    def test_settle_zero(self):
+        self.post_project("raclette")
+
+        # add members
+        self.app.post("/raclette/members/add", data={'name': 'alexis'})
+        self.app.post("/raclette/members/add", data={'name': 'fred'})
+        self.app.post("/raclette/members/add", data={'name': 'tata'})
+
+        # create bills
+        self.app.post("/raclette/add", data={
+            'date': '2016-12-31',
+            'what': u'fromage à raclette',
+            'payer': 1,
+            'payed_for': [1, 2, 3],
+            'amount': '10.0',
+        })
+
+        self.app.post("/raclette/add", data={
+            'date': '2016-12-31',
+            'what': u'red wine',
+            'payer': 2,
+            'payed_for': [1, 3],
+            'amount': '20',
+        })
+
+        self.app.post("/raclette/add", data={
+            'date': '2017-01-01',
+            'what': u'refund',
+            'payer': 3,
+            'payed_for': [2],
+            'amount': '13.33',
+        })
+        project  = models.Project.query.get('raclette')
+        transactions = project.get_transactions_to_settle_bill()
+        members = defaultdict(int)
+        # There should not be any zero-amount transfer after rounding
+        for t in transactions:
+            rounded_amount = round(t['amount'], 2)
+            self.assertNotEqual(0.0, rounded_amount,
+                                msg='%f is equal to zero after rounding' % t['amount'])
 
 
 class APITestCase(TestCase):

From b507a5afa1b4e3594a3a35f3aae08f7f38989338 Mon Sep 17 00:00:00 2001
From: Baptiste Jonglez <git@bitsofnetworks.org>
Date: Mon, 2 Jan 2017 14:52:59 +0100
Subject: [PATCH 2/3] Prevent transfers with a zero amount in the settle page

This workarounds a rounding issue caused by the (incorrect) usage of
floats for bill amounts.

This fixes #138
---
 budget/models.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/budget/models.py b/budget/models.py
index 852b3e1..b17fc55 100644
--- a/budget/models.py
+++ b/budget/models.py
@@ -61,9 +61,9 @@ class Project(db.Model):
         credits, debts, transactions = [],[],[]
         # Create lists of credits and debts
         for person in self.members:
-            if balance[person.id] > 0:
+            if round(balance[person.id], 2) > 0:
                 credits.append({"person": person, "balance": balance[person.id]})
-            elif balance[person.id] < 0:
+            elif round(balance[person.id], 2) < 0:
                 debts.append({"person": person, "balance": -balance[person.id]})
         # Try and find exact matches
         for credit in credits:

From d6cf89008fdb5e40395d3ccc879db2255f13e461 Mon Sep 17 00:00:00 2001
From: Baptiste Jonglez <git@bitsofnetworks.org>
Date: Mon, 2 Jan 2017 14:55:48 +0100
Subject: [PATCH 3/3] Workaround rounding issues when displaying balance of
 users

A user with a "0.00" balance would have either a "+0.00" in green or a
"-0.00" in red, depending on the exact value of the floating-point value.

Fix this by simply rounding to 2 digits before comparing to zero.
---
 budget/templates/list_bills.html   | 6 +++---
 budget/templates/settle_bills.html | 6 +++---
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/budget/templates/list_bills.html b/budget/templates/list_bills.html
index f081334..72b9032 100644
--- a/budget/templates/list_bills.html
+++ b/budget/templates/list_bills.html
@@ -65,7 +65,7 @@
     <div id="table_overflow">
     <table class="balance table">
     {% set balance = g.project.balance %}
-    {% for member in g.project.members | sort(attribute='name') if member.activated or balance[member.id] != 0 %}
+    {% for member in g.project.members | sort(attribute='name') if member.activated or balance[member.id]|round(2) != 0 %}
     <tr id="bal-member-{{ member.id }}" action={% if member.activated %}delete{% else %}reactivate{% endif %}>
         <td class="balance-name">{{ member.name }}
             <span class="light{% if not g.project.uses_weights %} extra-info{% endif %}">(x{{ member.weight|minimal_round(1) }})</span>
@@ -82,8 +82,8 @@
             <form class="action reactivate" action="{{ url_for(".reactivate", member_id=member.id) }}" method="POST">
                 <button type="submit">{{ _("reactivate") }}</button></form></td>
         {% endif %}
-        <td class="balance-value {% if balance[member.id] > 0 %}positive{% elif balance[member.id] < 0 %}negative{% endif %}">
-            {% if balance[member.id] > 0 %}+{% endif %}{{ "%.2f" | format(balance[member.id]) }}
+        <td class="balance-value {% if balance[member.id]|round(2) > 0 %}positive{% elif balance[member.id]|round(2) < 0 %}negative{% endif %}">
+            {% if balance[member.id]|round(2) > 0 %}+{% endif %}{{ "%.2f" | format(balance[member.id]) }}
         </td>
     </tr>
     {% endfor %}
diff --git a/budget/templates/settle_bills.html b/budget/templates/settle_bills.html
index 4066b16..16c60b3 100644
--- a/budget/templates/settle_bills.html
+++ b/budget/templates/settle_bills.html
@@ -11,11 +11,11 @@
     <div id="table_overflow">
     <table class="balance table">
     {% set balance = g.project.balance %}
-    {% for member in g.project.members | sort(attribute='name') if member.activated or balance[member.id] != 0 %}
+    {% for member in g.project.members | sort(attribute='name') if member.activated or balance[member.id]|round(2) != 0 %}
     <tr id="bal-member-{{ member.id }}" action={% if member.activated %}delete{% else %}reactivate{% endif %}>
         <td class="balance-name">{{ member.name }}</td>
-        <td class="balance-value {% if balance[member.id] > 0 %}positive{% elif balance[member.id] < 0 %}negative{% endif %}">
-            {% if balance[member.id] > 0 %}+{% endif %}{{ "%.2f" | format(balance[member.id]) }}
+        <td class="balance-value {% if balance[member.id]|round(2) > 0 %}positive{% elif balance[member.id]|round(2) < 0 %}negative{% endif %}">
+            {% if balance[member.id]|round(2) > 0 %}+{% endif %}{{ "%.2f" | format(balance[member.id]) }}
         </td>
     </tr>
     {% endfor %}