clients: cbc_proxy client inits lambda client

Using correct:
* key id
* secret key
* region

Signed-off-by: Toby Lorne <toby.lornewelch-richards@digital.cabinet-office.gov.uk>
Co-authored-by: Pea <pea.tyczynska@digital.cabinet-office.gov.uk>
Co-authored-by: Katie <katie.smith@digital.cabinet-office.gov.uk>

tests/app/clients/test_cbc_proxy.py

@@ -0,0 +1,27 @@
+import pytest
+
+from app.clients.cbc_proxy import CBCProxyClient
+
+
+@pytest.fixture(scope='function')
+def cbc_proxy(client, mocker):
+    client = CBCProxyClient()
+    current_app = mocker.Mock(config={
+        'CBC_PROXY_AWS_ACCESS_KEY_ID': 'cbc-proxy-aws-access-key-id',
+        'CBC_PROXY_AWS_SECRET_ACCESS_KEY': 'cbc-proxy-aws-secret-access-key',
+    })
+    client.init_app(current_app)
+    return client
+
+
+def test_cbc_proxy_lambda_client_has_correct_region(cbc_proxy):
+    assert cbc_proxy._lambda_client._client_config.region_name == 'eu-west-2'
+    pass
+
+
+def test_cbc_proxy_lambda_client_has_correct_keys(cbc_proxy):
+    key = cbc_proxy._lambda_client._request_signer._credentials.access_key
+    secret = cbc_proxy._lambda_client._request_signer._credentials.secret_key
+
+    assert key == 'cbc-proxy-aws-access-key-id'
+    assert secret == 'cbc-proxy-aws-secret-access-key'