From 0561a0050fb7d68c1cfac5877690e786d3d2c083 Mon Sep 17 00:00:00 2001
From: Wayne Metcalfe <waynemetcalfe@gmail.com>
Date: Thu, 26 Sep 2019 17:09:10 +0100
Subject: [PATCH] feat: implement logs tag_log_group

---
 IMPLEMENTATION_COVERAGE.md   |  2 +-
 moto/logs/models.py          | 12 ++++++++++++
 moto/logs/responses.py       |  5 +++++
 tests/test_logs/test_logs.py | 24 ++++++++++++++++++++++++
 4 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/IMPLEMENTATION_COVERAGE.md b/IMPLEMENTATION_COVERAGE.md
index aac1d3858..1377c67be 100644
--- a/IMPLEMENTATION_COVERAGE.md
+++ b/IMPLEMENTATION_COVERAGE.md
@@ -4090,7 +4090,7 @@
 - [ ] put_subscription_filter
 - [ ] start_query
 - [ ] stop_query
-- [ ] tag_log_group
+- [X] tag_log_group
 - [ ] test_metric_filter
 - [ ] untag_log_group
 
diff --git a/moto/logs/models.py b/moto/logs/models.py
index de23e7dfb..01738fa39 100644
--- a/moto/logs/models.py
+++ b/moto/logs/models.py
@@ -234,6 +234,12 @@ class LogGroup:
     def list_tags(self):
         return self.tags if self.tags else {}
 
+    def tag(self, tags):
+        if self.tags:
+            self.tags.update(tags)
+        else:
+            self.tags = tags
+
 
 class LogsBackend(BaseBackend):
     def __init__(self, region_name):
@@ -331,5 +337,11 @@ class LogsBackend(BaseBackend):
         log_group = self.groups[log_group_name]
         return log_group.list_tags()
 
+    def tag_log_group(self, log_group_name, tags):
+        if log_group_name not in self.groups:
+            raise ResourceNotFoundException()
+        log_group = self.groups[log_group_name]
+        log_group.tag(tags)
+
 
 logs_backends = {region.name: LogsBackend(region.name) for region in boto.logs.regions()}
diff --git a/moto/logs/responses.py b/moto/logs/responses.py
index fd6084f7c..0c8750ce2 100644
--- a/moto/logs/responses.py
+++ b/moto/logs/responses.py
@@ -142,3 +142,8 @@ class LogsResponse(BaseResponse):
             'tags': tags
         })
 
+    def tag_log_group(self):
+        log_group_name = self._get_param('logGroupName')
+        tags = self._get_param('tags')
+        self.logs_backend.tag_log_group(log_group_name, tags)
+        return ''
diff --git a/tests/test_logs/test_logs.py b/tests/test_logs/test_logs.py
index 61dd0ad3a..fced03363 100644
--- a/tests/test_logs/test_logs.py
+++ b/tests/test_logs/test_logs.py
@@ -243,3 +243,27 @@ def test_list_tags_log_group():
     assert response['tags'] == tags
 
     response = conn.delete_log_group(logGroupName=log_group_name)
+
+
+@mock_logs
+def test_tag_log_group():
+    conn = boto3.client('logs', 'us-west-2')
+    log_group_name = 'dummy'
+    tags = {'tag_key_1': 'tag_value_1'}
+    response = conn.create_log_group(logGroupName=log_group_name)
+
+    response = conn.tag_log_group(logGroupName=log_group_name, tags=tags)
+    response = conn.list_tags_log_group(logGroupName=log_group_name)
+    assert response['tags'] == tags
+
+    tags_with_added_value = {'tag_key_1': 'tag_value_1', 'tag_key_2': 'tag_value_2'}
+    response = conn.tag_log_group(logGroupName=log_group_name, tags={'tag_key_2': 'tag_value_2'})
+    response = conn.list_tags_log_group(logGroupName=log_group_name)
+    assert response['tags'] == tags_with_added_value
+
+    tags_with_updated_value = {'tag_key_1': 'tag_value_XX', 'tag_key_2': 'tag_value_2'}
+    response = conn.tag_log_group(logGroupName=log_group_name, tags={'tag_key_1': 'tag_value_XX'})
+    response = conn.list_tags_log_group(logGroupName=log_group_name)
+    assert response['tags'] == tags_with_updated_value
+
+    response = conn.delete_log_group(logGroupName=log_group_name)