Add simple test for recursive loading

tests/testdata/testconfigs/base_config.json

@@ -0,0 +1,12 @@
+{
+    "stake_currency": "",
+    "dry_run": true,
+    "exchange": {
+        "name": "",
+        "key": "",
+        "secret": "",
+        "pair_whitelist": [],
+        "ccxt_async_config": {
+        }
+    }
+}

tests/testdata/testconfigs/pricing.json

@@ -0,0 +1,21 @@
+{
+    "entry_pricing": {
+        "price_side": "same",
+        "use_order_book": true,
+        "order_book_top": 1,
+        "price_last_balance": 0.0,
+        "check_depth_of_market": {
+            "enabled": false,
+            "bids_to_ask_delta": 1
+        }
+    },
+    "exit_pricing":{
+        "price_side": "same",
+        "use_order_book": true,
+        "order_book_top": 1,
+        "price_last_balance": 0.0
+    },
+    "files": [
+        "pricing2.json"
+    ]
+}

tests/testdata/testconfigs/pricing2.json

@@ -0,0 +1,18 @@
+{
+    "entry_pricing": {
+        "price_side": "same",
+        "use_order_book": true,
+        "order_book_top": 1,
+        "price_last_balance": 0.0,
+        "check_depth_of_market": {
+            "enabled": false,
+            "bids_to_ask_delta": 1
+        }
+    },
+    "exit_pricing":{
+        "price_side": "other",
+        "use_order_book": true,
+        "order_book_top": 1,
+        "price_last_balance": 0.0
+    }
+}

tests/testdata/testconfigs/recursive.json

@@ -0,0 +1,6 @@
+{
+    // This file fails as it's loading itself over and over
+    "files": [
+        "./recursive.json"
+    ]
+}

tests/testdata/testconfigs/testconfig.json

@@ -0,0 +1,6 @@
+{
+    "files": [
+        "base_config.json",
+        "pricing.json"
+    ]
+}