Implement APIGateway get_base_path_mappings (#4496)

moto/apigateway/models.py

@@ -1758,6 +1758,13 @@ class APIGatewayBackend(BaseBackend):
         self.base_path_mappings[domain_name][new_base_path] = new_base_path_mapping
         return new_base_path_mapping
 
+    def get_base_path_mappings(self, domain_name):
+
+        if domain_name not in self.domain_names:
+            raise DomainNameNotFound()
+
+        return list(self.base_path_mappings[domain_name].values())
+
 
 apigateway_backends = {}
 for region_name in Session().get_available_regions("apigateway"):

moto/apigateway/responses.py

@@ -859,8 +859,8 @@ class APIGatewayResponse(BaseResponse):
 
         try:
             if self.method == "GET":
-                # TODO implements
-                pass
+                base_path_mappings = self.backend.get_base_path_mappings(domain_name)
+                return 200, {}, json.dumps({"item": base_path_mappings})
             elif self.method == "POST":
                 base_path = self._get_param("basePath")
                 rest_api_id = self._get_param("restApiId")
@@ -872,5 +872,7 @@ class APIGatewayResponse(BaseResponse):
                 return 201, {}, json.dumps(base_path_mapping_resp)
         except BadRequestException as e:
             return self.error("BadRequestException", e.message)
+        except NotFoundException as e:
+            return self.error("NotFoundException", e.message, 404)
         except ConflictException as e:
             return self.error("ConflictException", e.message, 409)

tests/test_apigateway/test_apigateway.py

@@ -2502,3 +2502,60 @@ def test_create_base_path_mapping_with_duplicate_base_path():
     )
     ex.value.response["Error"]["Code"].should.equal("ConflictException")
     ex.value.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(409)
+
+
+@mock_apigateway
+def test_get_base_path_mappings():
+    client = boto3.client("apigateway", region_name="us-west-2")
+    domain_name = "testDomain"
+    test_certificate_name = "test.certificate"
+    client.create_domain_name(
+        domainName=domain_name, certificateName=test_certificate_name
+    )
+
+    response = client.create_rest_api(name="my_api", description="this is my api")
+    api_id = response["id"]
+    stage_name = "dev"
+    create_method_integration(client, api_id)
+    client.create_deployment(
+        restApiId=api_id, stageName=stage_name, description="1.0.1"
+    )
+
+    client.create_base_path_mapping(domainName=domain_name, restApiId=api_id)
+    client.create_base_path_mapping(
+        domainName=domain_name, restApiId=api_id, basePath="v1"
+    )
+    client.create_base_path_mapping(
+        domainName=domain_name, restApiId=api_id, basePath="v2", stage=stage_name
+    )
+
+    response = client.get_base_path_mappings(domainName=domain_name)
+    response["ResponseMetadata"]["HTTPStatusCode"].should.equal(200)
+
+    items = response["items"]
+
+    items[0]["basePath"].should.equal("(none)")
+    items[0]["restApiId"].should.equal(api_id)
+    items[0].should_not.have.key("stage")
+
+    items[1]["basePath"].should.equal("v1")
+    items[1]["restApiId"].should.equal(api_id)
+    items[1].should_not.have.key("stage")
+
+    items[2]["basePath"].should.equal("v2")
+    items[2]["restApiId"].should.equal(api_id)
+    items[2]["stage"].should.equal(stage_name)
+
+
+@mock_apigateway
+def test_get_base_path_mappings_with_unknown_domain():
+    client = boto3.client("apigateway", region_name="us-west-2")
+
+    with pytest.raises(ClientError) as ex:
+        client.get_base_path_mappings(domainName="unknown-domain")
+
+    ex.value.response["Error"]["Message"].should.equal(
+        "Invalid domain name identifier specified"
+    )
+    ex.value.response["Error"]["Code"].should.equal("NotFoundException")
+    ex.value.response["ResponseMetadata"]["HTTPStatusCode"].should.equal(404)