Make example part of test suite

Author: Marcus Olsson

README.md

@@ -42,18 +42,19 @@ Here's a sample entry (prettified) from the example:
 
 ```json
 {
-  "context": {    "reportLocation": {
-      "filePath": "example/main.go",
-      "lineNumber": 22,
-      "functionName": "main"
-    }
-  },
-  "message": "unable to parse integer: strconv.ParseInt: parsing \"text\": invalid syntax",
   "serviceContext": {
     "service": "test-service",
     "version": "v0.1.0"
   },
-  "severity": "ERROR"
+  "message": "unable to parse integer: strconv.ParseInt: parsing \"text\": invalid syntax",
+  "severity": "ERROR",
+  "context": {
+    "reportLocation": {
+      "filePath": "github.com/TV4/logrus-stackdriver-formatter/example_test.go",
+      "lineNumber": 21,
+      "functionName": "ExampleLogError"
+    }
+  }
 }
 ```
 

example/main.go

@@ -0,0 +1,29 @@
+package stackdriver_test
+
+import (
+	"os"
+	"strconv"
+
+	stackdriver "github.com/TV4/logrus-stackdriver-formatter"
+	"github.com/sirupsen/logrus"
+)
+
+func ExampleLogError() {
+	logger := logrus.New()
+	logger.Out = os.Stdout
+	logger.Formatter = stackdriver.NewFormatter(
+		stackdriver.WithService("test-service"),
+		stackdriver.WithVersion("v0.1.0"),
+	)
+
+	logger.Info("application up and running")
+
+	_, err := strconv.ParseInt("text", 10, 64)
+	if err != nil {
+		logger.WithError(err).Errorln("unable to parse integer")
+	}
+
+	// Output:
+	// {"message":"application up and running","severity":"INFO","context":{}}
+	// {"serviceContext":{"service":"test-service","version":"v0.1.0"},"message":"unable to parse integer: strconv.ParseInt: parsing \"text\": invalid syntax","severity":"ERROR","context":{"reportLocation":{"filePath":"github.com/TV4/logrus-stackdriver-formatter/example_test.go","lineNumber":23,"functionName":"ExampleLogError"}}}
+}