do not allow None as value of image_tags

moto/ecr/models.py

@@ -99,7 +99,7 @@ class Image(BaseObject):
 
     def __init__(self, tag, manifest, repository, digest=None, registry_id=DEFAULT_REGISTRY_ID):
         self.image_tag = tag
-        self.image_tags = [tag]
+        self.image_tags = [tag] if tag is not None else []
         self.image_manifest = manifest
         self.image_size_in_bytes = 50 * 1024 * 1024
         self.repository = repository
@@ -121,7 +121,7 @@ class Image(BaseObject):
 
     def update_tag(self, tag):
         self.image_tag = tag
-        if tag not in self.image_tags:
+        if tag not in self.image_tags and tag is not None:
             self.image_tags.append(tag)
 
     @property
@@ -235,7 +235,7 @@ class ECRBackend(BaseBackend):
                 found = False
                 for image in repository.images:
                     if (('imageDigest' in image_id and image.get_image_digest() == image_id['imageDigest']) or
-                            ('imageTag' in image_id and image.image_tag == image_id['imageTag'])):
+                            ('imageTag' in image_id and image_id['imageTag'] in image.image_tags)):
                         found = True
                         response.add(image)
                 if not found:

tests/test_ecr/test_ecr_boto3.py

@@ -385,6 +385,68 @@ def test_describe_images_by_tag():
         image_detail['imageDigest'].should.equal(put_response['imageId']['imageDigest'])
 
 
+@mock_ecr
+def test_describe_images_tags_should_not_contain_empty_tag1():
+    client = boto3.client('ecr', region_name='us-east-1')
+    _ = client.create_repository(
+        repositoryName='test_repository'
+    )
+
+    manifest = _create_image_manifest()
+    client.put_image(
+        repositoryName='test_repository',
+        imageManifest=json.dumps(manifest)
+    )
+
+    tags = ['v1', 'v2', 'latest']
+    for tag in tags:
+        client.put_image(
+            repositoryName='test_repository',
+            imageManifest=json.dumps(manifest),
+            imageTag=tag
+        )
+
+    response = client.describe_images(repositoryName='test_repository', imageIds=[{'imageTag': tag}])
+    len(response['imageDetails']).should.be(1)
+    image_detail = response['imageDetails'][0]
+    len(image_detail['imageTags']).should.equal(3)
+    image_detail['imageTags'].should.be.equal(tags)
+
+
+@mock_ecr
+def test_describe_images_tags_should_not_contain_empty_tag2():
+    client = boto3.client('ecr', region_name='us-east-1')
+    _ = client.create_repository(
+        repositoryName='test_repository'
+    )
+
+    manifest = _create_image_manifest()
+    tags = ['v1', 'v2']
+    for tag in tags:
+        client.put_image(
+            repositoryName='test_repository',
+            imageManifest=json.dumps(manifest),
+            imageTag=tag
+        )
+
+    client.put_image(
+        repositoryName='test_repository',
+        imageManifest=json.dumps(manifest)
+    )
+
+    client.put_image(
+        repositoryName='test_repository',
+        imageManifest=json.dumps(manifest),
+        imageTag='latest'
+    )
+
+    response = client.describe_images(repositoryName='test_repository', imageIds=[{'imageTag': tag}])
+    len(response['imageDetails']).should.be(1)
+    image_detail = response['imageDetails'][0]
+    len(image_detail['imageTags']).should.equal(3)
+    image_detail['imageTags'].should.be.equal(['v1', 'v2', 'latest'])
+
+
 @mock_ecr
 def test_describe_repository_that_doesnt_exist():
     client = boto3.client('ecr', region_name='us-east-1')