Test setup and documentation fixes (#584)

* Fix `make json schema` for macOS

Use gtar instead of tar

* Add psutil to requirement-base

Had a unit test failure without it installed:

test_send_remote_failover_sync_non_transport_exception_error

* Add some testing artifacts to .gitignore

* Fix a couple of testing documentation issues

* Fix psutil test properly

test_send_remote_failover_sync_non_transport_exception_error isn't
concerned with metrics, so just disable the metrics sets.

Author: basepi

.gitignore

@@ -25,3 +25,5 @@ coverage
 /testdb.sql
 venv
 benchmarks/result*
+coverage.xml
+tests/python-agent-junit.xml

docs/run-tests-locally.asciidoc

@@ -55,5 +55,18 @@ We run the test suite on different combinations of Python versions and web frame
 ----
 $ ./tests/scripts/docker/run_tests.sh python-version framework-version <pip-cache-dir>
 ----
-NOTE: The `python-version` must be of format `python:version`, e.g. `python:3.6` or `pypy:2`.
+NOTE: The `python-version` must be of format `python-version`, e.g. `python-3.6` or `pypy-2`.
 The `framework` must be of format `framework-version`, e.g. `django-1.10` or `flask-0.12`.
+
+==== Integration testing
+
+Check out https://github.com/elastic/apm-integration-testing for resources for
+setting up full end-to-end testing environments. For example, to spin up
+an environment with the https://github.com/basepi/opbeans-python[opbeans Django app],
+with version 7.3 of the elastic stack and the apm-python-agent from your local
+checkout, you might do something like this:
+
+[source,bash]
+----
+$ ./scripts/compose.py start 7.3 --with-agent-python-django --with-opbeans-python --opbeans-python-agent-local-repo=~/elastic/apm-agent-python

+----

tests/client/client_tests.py

@@ -250,6 +250,7 @@ def test_send_remote_failover_sync_non_transport_exception_error(should_try, htt
         secret_token="secret",
         transport_class="elasticapm.transport.http.Transport",
         metrics_interval="0ms",
+        metrics_sets=[],
     )
     # test error
     http_send.side_effect = ValueError("oopsie")

tests/scripts/download_json_schema.sh

@@ -7,7 +7,11 @@ download_schema()
     rm -rf ${1} && mkdir -p ${1}
     for run in 1 2 3 4 5
     do
-        curl --silent --fail https://codeload.github.com/elastic/apm-server/tar.gz/${2} | tar xzvf - --wildcards --directory=${1} --strip-components=1 "*/docs/spec/*"
+        if [ -x "$(command -v gtar)" ]; then
+            curl --silent --fail https://codeload.github.com/elastic/apm-server/tar.gz/${2} | gtar xzvf - --wildcards --directory=${1} --strip-components=1 "*/docs/spec/*"
+        else
+            curl --silent --fail https://codeload.github.com/elastic/apm-server/tar.gz/${2} | tar xzvf - --wildcards --directory=${1} --strip-components=1 "*/docs/spec/*"
+        fi
         result=$?
         if [ $result -eq 0 ]; then break; fi
         sleep 1