Merge pull request #277 from xocasdashdash/updated-docs

Updated docs and added good/bad example yaml

README.md

@@ -198,6 +198,16 @@ mappings:
 The metric name can also contain references to regex matches. The mapping above
 could be written as:
 
+```yaml
+mappings:
+- match: "test\\.(\\w+)\\.(\\w+)\\.counter"
+  match_type: regex
+  name: "${2}_total"
+  labels:
+    provider: "$1"
+```
+
+Be aware about yaml escape rules as a mapping like the following one will not work. 
 ```yaml 
 mappings:
 - match: "test\.(\w+)\.(\w+)\.counter"

pkg/mapper/mapper_test.go

@@ -842,6 +842,31 @@ mappings:
 			configBad:      true,
 			expectedAction: ActionTypeDrop,
 		},
+		{
+			// valid yaml example
+			config: `---
+mappings:
+- match: "test\\.(\\w+)\\.(\\w+)\\.counter"
+  match_type: regex
+  name: "${2}_total"
+  labels:
+    provider: "$1"
+`,
+			configBad:      false,
+			expectedAction: ActionTypeMap,
+		},
+		{
+			// invalid yaml example
+			config: `---
+mappings:
+- match: "test\.(\w+)\.(\w+)\.counter"
+  match_type: regex
+  name: "${2}_total"
+  labels:
+    provider: "$1"
+`,
+			configBad: true,
+		},
 	}
 
 	for i, scenario := range scenarios {