New rule: get-return (#23)

* Adds rule superfluous-else (an extension of indent-error-flow)

* Fix superfluous-else rule struct namming.

* Adds superfuous-else rule to the rules table

* Adds confusing-naming rule

* adds multifile test

* clean-up

* clean master

* running version

* isGetter now checks for non lowercase characters

README.md

@@ -210,6 +210,8 @@ List of all available rules. The rules ported from `golint` are left unchanged a
 | `file-header`         | string | Header which each file should have.                              |    no    |  no   |
 | `empty-block`         |  n/a   | Warns on empty code blocks                                       |    no    |  no   |
 | `superfluous-else`    |  n/a   | Prevents redundant else statements (extends `indent-error-flow`) |    no    |  no   |
+| `confusing-naming`    |  n/a   | Warns on methods with names that differ only by capitalization   |    no    |  no   |
+| `get-return      `    |  n/a   | Warns on getters that do not yield any result                    |    no    |  no   |
 
 ## Available Formatters
 

config.go

@@ -49,6 +49,7 @@ var allRules = append([]lint.Rule{
 	&rule.FileHeaderRule{},
 	&rule.EmptyBlockRule{},
 	&rule.SuperfluousElseRule{},
+	&rule.GetReturnRule{},
 }, defaultRules...)
 
 var allFormatters = []lint.Formatter{

fixtures/get-return.go

@@ -0,0 +1,29 @@
+package fixtures
+
+func getfoo() {
+
+}
+
+func getBar(a, b int) { // MATCH /function 'getBar' seems to be a getter but it does not return any result/
+
+}
+
+func Getbaz(a string, b int) {
+
+}
+
+func GetTaz(a string, b int) string {
+
+}
+
+func (t *t) GetTaz(a string, b int) string {
+
+}
+
+func (t *t) GetSaz(a string, b int) { // MATCH /function 'GetSaz' seems to be a getter but it does not return any result/
+
+}
+
+func GetQux(a string, b int, c int, d string, e int64) { // MATCH /function 'GetQux' seems to be a getter but it does not return any result/
+
+}

rule/get-return.go

@@ -0,0 +1,71 @@
+package rule
+
+import (
+	"fmt"
+	"go/ast"
+	"strings"
+
+	"github.com/mgechev/revive/lint"
+)
+
+// GetReturnRule lints given else constructs.
+type GetReturnRule struct{}
+
+// Apply applies the rule to given file.
+func (r *GetReturnRule) Apply(file *lint.File, arguments lint.Arguments) []lint.Failure {
+	var failures []lint.Failure
+
+	onFailure := func(failure lint.Failure) {
+		failures = append(failures, failure)
+	}
+
+	w := lintReturnRule{onFailure}
+	ast.Walk(w, file.AST)
+	return failures
+}
+
+// Name returns the rule name.
+func (r *GetReturnRule) Name() string {
+	return "get-return"
+}
+
+type lintReturnRule struct {
+	onFailure func(lint.Failure)
+}
+
+func isGetter(name string) bool {
+	if strings.HasPrefix(strings.ToUpper(name), "GET") {
+		if len(name) > 3 {
+			c := name[3]
+			return !(c >= 'a' && c <= 'z')
+		}
+	}
+
+	return false
+}
+
+func hasResults(rs *ast.FieldList) bool {
+	return rs != nil && len(rs.List) > 0
+}
+
+func (w lintReturnRule) Visit(node ast.Node) ast.Visitor {
+	fd, ok := node.(*ast.FuncDecl)
+	if !ok {
+		return w
+	}
+
+	if !isGetter(fd.Name.Name) {
+		return w
+	}
+	if !hasResults(fd.Type.Results) {
+		w.onFailure(lint.Failure{
+			Confidence: 0.8,
+			Node:       fd,
+			Category:   "logic",
+			URL:        "#get-return",
+			Failure:    fmt.Sprintf("function '%s' seems to be a getter but it does not return any result", fd.Name.Name),
+		})
+	}
+
+	return w
+}

test/get-return_test.go

@@ -0,0 +1,11 @@
+package test
+
+import (
+	"testing"
+
+	"github.com/mgechev/revive/rule"
+)
+
+func TestGetReturn(t *testing.T) {
+	testRule(t, "get-return", &rule.GetReturnRule{})
+}