add graylog test and fix invalid JSON handling

plugins/inputs/graylog/graylog.go

@@ -1,18 +1,18 @@
 package graylog
 
 import (
-	"bytes"
-	"encoding/json"
 	"errors"
 	"fmt"
+	"strconv"
+	"bytes"
+	"regexp"
 	"io/ioutil"
 	"net/http"
 	"net/url"
-	"regexp"
-	"strconv"
 	"strings"
 	"sync"
 	"time"
+	"encoding/json"
 
 	"github.com/influxdata/telegraf"
 	"github.com/influxdata/telegraf/internal"
@@ -202,7 +202,7 @@ func (h *GrayLog) gatherServer(
 		return err
 	}
 	if err := json.Unmarshal([]byte(resp), &dat); err != nil {
-		panic(err)
+    return err
 	}
 	if rec, ok := dat["metrics"].([]interface{}); ok {
 		for _, metric := range rec {
@@ -222,7 +222,7 @@ func (h *GrayLog) gatherServer(
 		for k, v := range metric.Fields() {
 			re, _ := regexp.Compile(`metrics_([0-9]+)`)
 			match := re.FindAllStringSubmatch(k, -1)
-			if match != nil {
+			if(match != nil) {
 				i, _ := strconv.Atoi(match[0][1])
 				fields[name_list[i]] = v
 			} 

plugins/inputs/graylog/graylog_test.go

@@ -0,0 +1,187 @@
+package graylog
+
+import (
+//	"fmt"
+	"io/ioutil"
+	"net/http"
+//	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/influxdata/telegraf/testutil"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+const validJSON = `
+  {
+    "total": 2,
+    "metrics": [
+      {
+        "full_name": "jvm.cl.loaded",
+        "metric": {
+          "value": 18910
+        },
+        "name": "loaded",
+        "type": "gauge"
+      },
+      {
+        "full_name": "jvm.memory.pools.Metaspace.committed",
+        "metric": {
+          "value": 108040192
+        },
+        "name": "committed",
+        "type": "gauge"
+      }
+    ]
+  }`
+
+
+var expectedFields = map[string]interface{}{
+	"jvm.memory.pools.Metaspace.committed":         float64(108040192),
+	"jvm.cl.loaded":         float64(18910),
+}
+
+const invalidJSON = "I don't think this is JSON"
+
+const empty = ""
+
+type mockHTTPClient struct {
+	responseBody string
+	statusCode   int
+}
+
+// Mock implementation of MakeRequest. Usually returns an http.Response with
+// hard-coded responseBody and statusCode. However, if the request uses a
+// nonstandard method, it uses status code 405 (method not allowed)
+func (c *mockHTTPClient) MakeRequest(req *http.Request) (*http.Response, error) {
+	resp := http.Response{}
+	resp.StatusCode = c.statusCode
+
+	// basic error checking on request method
+	allowedMethods := []string{"GET", "HEAD", "POST", "PUT", "DELETE", "TRACE", "CONNECT"}
+	methodValid := false
+	for _, method := range allowedMethods {
+		if req.Method == method {
+			methodValid = true
+			break
+		}
+	}
+
+	if !methodValid {
+		resp.StatusCode = 405 // Method not allowed
+	}
+
+	resp.Body = ioutil.NopCloser(strings.NewReader(c.responseBody))
+	return &resp, nil
+}
+
+func (c *mockHTTPClient) SetHTTPClient(_ *http.Client) {
+}
+
+func (c *mockHTTPClient) HTTPClient() *http.Client {
+	return nil
+}
+
+// Generates a pointer to an HttpJson object that uses a mock HTTP client.
+// Parameters:
+//     response  : Body of the response that the mock HTTP client should return
+//     statusCode: HTTP status code the mock HTTP client should return
+//
+// Returns:
+//     *HttpJson: Pointer to an HttpJson object that uses the generated mock HTTP client
+func genMockGrayLog(response string, statusCode int) []*GrayLog {
+	return []*GrayLog{
+		&GrayLog{
+			client: &mockHTTPClient{responseBody: response, statusCode: statusCode},
+			Servers: []string{
+				"http://localhost:12900/system/metrics/multiple",
+			},
+			Name:   "my_webapp",
+			Metrics: []string{
+         "jvm.cl.loaded",
+			},
+			Headers: map[string]string{
+        "Content-Type" : "application/json",
+        "Accept" : "application/json",
+        "Authorization" : "Basic DESfdsfffoffo",
+			},
+		},
+		&GrayLog{
+			client: &mockHTTPClient{responseBody: response, statusCode: statusCode},
+      Servers: []string{
+				"http://server2:12900/system/metrics/multiple",
+			},
+			Name:   "other_webapp",
+      Metrics: []string{
+         "jvm.memory.pools.Metaspace.committed",
+			},
+			Headers: map[string]string{
+        "Content-Type" : "application/json",
+        "Accept" : "application/json",
+        "Authorization" : "Basic DESfdsfffoffo",
+			},
+			TagKeys: []string{
+				"role",
+				"build",
+			},
+		},
+	}
+}
+
+// Test that the proper values are ignored or collected
+func TestNormalResponse(t *testing.T) {
+	graylog := genMockGrayLog(validJSON, 200)
+
+	for _, service := range graylog {
+		var acc testutil.Accumulator
+		err := service.Gather(&acc)
+		require.NoError(t, err)
+		assert.Equal(t, 3, acc.NFields())
+		// Set responsetime
+		for _, p := range acc.Metrics {
+			p.Fields["response_time"] = 1.0
+		}
+
+		for _, srv := range service.Servers {
+			tags := map[string]string{"server": srv}
+			mname := "graylog_" + service.Name
+			expectedFields["response_time"] = 1.0
+			acc.AssertContainsTaggedFields(t, mname, expectedFields, tags)
+		}
+	}
+}
+
+
+// Test response to HTTP 500
+func TestHttpJson500(t *testing.T) {
+	graylog := genMockGrayLog(validJSON, 500)
+
+	var acc testutil.Accumulator
+	err := graylog[0].Gather(&acc)
+
+	assert.NotNil(t, err)
+	assert.Equal(t, 0, acc.NFields())
+}
+
+// Test response to malformed JSON
+func TestHttpJsonBadJson(t *testing.T) {
+	graylog := genMockGrayLog(invalidJSON, 200)
+
+	var acc testutil.Accumulator
+	err := graylog[0].Gather(&acc)
+
+	assert.NotNil(t, err)
+	assert.Equal(t, 0, acc.NFields())
+}
+
+// Test response to empty string as response objectgT
+func TestHttpJsonEmptyResponse(t *testing.T) {
+	graylog := genMockGrayLog(empty, 200)
+
+	var acc testutil.Accumulator
+	err := graylog[0].Gather(&acc)
+
+	assert.NotNil(t, err)
+	assert.Equal(t, 0, acc.NFields())
+}