Prevent null pointer exception in Sonarqube (#334)

* fix(formatters) null value causes npe in sonarqube

the json encoding of uninitialized arrays is null. this causes a npe in
sonarqube tool. we should return an empty array rather than a null value
here.

relates to: #333

output/formatter.go

@@ -117,8 +117,8 @@ func reportSonarqube(rootPaths []string, w io.Writer, data *reportInfo) error {
 	return err
 }
 
-func convertToSonarIssues(rootPaths []string, data *reportInfo) (sonarIssues, error) {
-	var si sonarIssues
+func convertToSonarIssues(rootPaths []string, data *reportInfo) (*sonarIssues, error) {
+	si := &sonarIssues{[]sonarIssue{}}
 	for _, issue := range data.Issues {
 		var sonarFilePath string
 		for _, rootPath := range rootPaths {

output/formatter_test.go

@@ -32,7 +32,7 @@ var _ = Describe("Formatter", func() {
 					NumFound: 0,
 				},
 			}
-			want := sonarIssues{
+			want := &sonarIssues{
 				SonarIssues: []sonarIssue{
 					{
 						EngineID: "gosec",
@@ -56,7 +56,7 @@ var _ = Describe("Formatter", func() {
 
 			issues, err := convertToSonarIssues([]string{rootPath}, data)
 			Expect(err).ShouldNot(HaveOccurred())
-			Expect(issues).To(Equal(want))
+			Expect(*issues).To(Equal(*want))
 		})
 
 		It("it should parse the report info with files in subfolders", func() {
@@ -80,7 +80,7 @@ var _ = Describe("Formatter", func() {
 					NumFound: 0,
 				},
 			}
-			want := sonarIssues{
+			want := &sonarIssues{
 				SonarIssues: []sonarIssue{
 					{
 						EngineID: "gosec",
@@ -104,7 +104,7 @@ var _ = Describe("Formatter", func() {
 
 			issues, err := convertToSonarIssues([]string{rootPath}, data)
 			Expect(err).ShouldNot(HaveOccurred())
-			Expect(issues).To(Equal(want))
+			Expect(*issues).To(Equal(*want))
 		})
 		It("it should not parse the report info for files from other projects", func() {
 			data := &reportInfo{
@@ -127,15 +127,15 @@ var _ = Describe("Formatter", func() {
 					NumFound: 0,
 				},
 			}
-			want := sonarIssues{
-				SonarIssues: nil,
+			want := &sonarIssues{
+				SonarIssues: []sonarIssue{},
 			}
 
 			rootPath := "/home/src/project2"
 
 			issues, err := convertToSonarIssues([]string{rootPath}, data)
 			Expect(err).ShouldNot(HaveOccurred())
-			Expect(issues).To(Equal(want))
+			Expect(*issues).To(Equal(*want))
 		})
 
 		It("it should parse the report info for multiple projects projects", func() {
@@ -168,7 +168,7 @@ var _ = Describe("Formatter", func() {
 					NumFound: 0,
 				},
 			}
-			want := sonarIssues{
+			want := &sonarIssues{
 				SonarIssues: []sonarIssue{
 					{
 						EngineID: "gosec",
@@ -207,7 +207,7 @@ var _ = Describe("Formatter", func() {
 
 			issues, err := convertToSonarIssues(rootPaths, data)
 			Expect(err).ShouldNot(HaveOccurred())
-			Expect(issues).To(Equal(want))
+			Expect(*issues).To(Equal(*want))
 		})
 	})
 })