Fix bug: ginkgolinter ignores the Error() method

as in:

```go
Expect(func() (int, error) {return 42, nil}()).Error().ToNot(HaveOccurred())
```

Author: nunnatsa

analyzer_test.go

@@ -101,6 +101,10 @@ func TestAllUseCases(t *testing.T) {
 			testName: "nil error-func variable",
 			testData: "a/issue-171",
 		},
+		{
+			testName: "respect the Error() method",
+			testData: "a/issue-173",
+		},
 		{
 			testName: "matchError with func return error-func",
 			testData: "a/issue-174",

internal/expression/actual/actual.go

@@ -21,13 +21,13 @@ type Actual struct {
 	actualOffset int
 }
 
-func New(origExpr, cloneExpr *ast.CallExpr, orig *ast.CallExpr, clone *ast.CallExpr, pass *analysis.Pass, handler gomegahandler.Handler, timePkg string) (*Actual, bool) {
+func New(origExpr, cloneExpr *ast.CallExpr, orig *ast.CallExpr, clone *ast.CallExpr, pass *analysis.Pass, handler gomegahandler.Handler, timePkg string, errMethodExists bool) (*Actual, bool) {
 	funcName, ok := handler.GetActualFuncName(orig)
 	if !ok {
 		return nil, false
 	}
 
-	arg, actualOffset := getActualArgPayload(orig, clone, pass, funcName)
+	arg, actualOffset := getActualArgPayload(orig, clone, pass, funcName, errMethodExists)
 	if arg == nil {
 		return nil, false
 	}

internal/expression/actual/actualarg.go

@@ -28,6 +28,7 @@ const (
 	ErrFuncActualArgType
 	GomegaParamArgType
 	MultiRetsArgType
+	ErrorMethodArgType
 
 	ErrorTypeArgType
 
@@ -39,15 +40,17 @@ func (a ArgType) Is(val ArgType) bool {
 	return a&val != 0
 }
 
-func getActualArgPayload(origActualExpr, actualExprClone *ast.CallExpr, pass *analysis.Pass, actualMethodName string) (ArgPayload, int) {
+func getActualArgPayload(origActualExpr, actualExprClone *ast.CallExpr, pass *analysis.Pass, actualMethodName string, errMethodExists bool) (ArgPayload, int) {
 	origArgExpr, argExprClone, actualOffset, isGomegaExpr := getActualArg(origActualExpr, actualExprClone, actualMethodName, pass)
 	if !isGomegaExpr {
 		return nil, 0
 	}
 
 	var arg ArgPayload
 
-	if value.IsExprError(pass, origArgExpr) {
+	if errMethodExists {
+		arg = &ErrorMethodPayload{}
+	} else if value.IsExprError(pass, origArgExpr) {
 		arg = newErrPayload(origArgExpr, argExprClone, pass)
 	} else {
 		switch expr := origArgExpr.(type) {
@@ -183,6 +186,12 @@ func (*ErrPayload) ArgType() ArgType {
 	return ErrActualArgType | ErrorTypeArgType
 }
 
+type ErrorMethodPayload struct{}
+
+func (ErrorMethodPayload) ArgType() ArgType {
+	return ErrorMethodArgType | ErrorTypeArgType
+}
+
 func parseBinaryExpr(origActualExpr, argExprClone *ast.BinaryExpr, pass *analysis.Pass) ArgPayload {
 	left, right, op := origActualExpr.X, origActualExpr.Y, origActualExpr.Op
 	replace := false

internal/expression/expression.go

@@ -52,7 +52,9 @@ func New(origExpr *ast.CallExpr, pass *analysis.Pass, handler gomegahandler.Hand
 	exprClone := astcopy.CallExpr(origExpr)
 	selClone := exprClone.Fun.(*ast.SelectorExpr)
 
-	origActual := handler.GetActualExpr(origSel)
+	errMethodExists := false
+
+	origActual := handler.GetActualExpr(origSel, &errMethodExists)
 	if origActual == nil {
 		return nil, false
 	}
@@ -62,7 +64,7 @@ func New(origExpr *ast.CallExpr, pass *analysis.Pass, handler gomegahandler.Hand
 		return nil, false
 	}
 
-	actl, ok := actual.New(origExpr, exprClone, origActual, actualClone, pass, handler, timePkg)
+	actl, ok := actual.New(origExpr, exprClone, origActual, actualClone, pass, handler, timePkg, errMethodExists)
 	if !ok {
 		return nil, false
 	}

internal/gomegahandler/dothandler.go

@@ -51,7 +51,7 @@ func (dotHandler) GetNewWrapperMatcher(name string, existing *ast.CallExpr) *ast
 	}
 }
 
-func (h dotHandler) GetActualExpr(assertionFunc *ast.SelectorExpr) *ast.CallExpr {
+func (h dotHandler) GetActualExpr(assertionFunc *ast.SelectorExpr, errMethodExists *bool) *ast.CallExpr {
 	actualExpr, ok := assertionFunc.X.(*ast.CallExpr)
 	if !ok {
 		return nil
@@ -66,7 +66,11 @@ func (h dotHandler) GetActualExpr(assertionFunc *ast.SelectorExpr) *ast.CallExpr
 				return actualExpr
 			}
 		} else {
-			return h.GetActualExpr(fun)
+			if fun.Sel.Name == "Error" {
+				*errMethodExists = true
+			}
+
+			return h.GetActualExpr(fun, errMethodExists)
 		}
 	}
 	return nil

internal/gomegahandler/handler.go

@@ -18,7 +18,7 @@ type Handler interface {
 	// ReplaceFunction replaces the function with another one, for fix suggestions
 	ReplaceFunction(*ast.CallExpr, *ast.Ident)
 
-	GetActualExpr(assertionFunc *ast.SelectorExpr) *ast.CallExpr
+	GetActualExpr(assertionFunc *ast.SelectorExpr, errMethodExists *bool) *ast.CallExpr
 
 	GetActualExprClone(origFunc, funcClone *ast.SelectorExpr) *ast.CallExpr
 

internal/gomegahandler/namedhandler.go

@@ -51,7 +51,7 @@ func (g nameHandler) isGomegaVar(x ast.Expr) bool {
 	return gomegainfo.IsGomegaVar(x, g.pass)
 }
 
-func (g nameHandler) GetActualExpr(assertionFunc *ast.SelectorExpr) *ast.CallExpr {
+func (g nameHandler) GetActualExpr(assertionFunc *ast.SelectorExpr, errMethodExists *bool) *ast.CallExpr {
 	actualExpr, ok := assertionFunc.X.(*ast.CallExpr)
 	if !ok {
 		return nil
@@ -69,7 +69,10 @@ func (g nameHandler) GetActualExpr(assertionFunc *ast.SelectorExpr) *ast.CallExp
 				return actualExpr
 			}
 		} else {
-			return g.GetActualExpr(fun)
+			if fun.Sel.Name == "Error" {
+				*errMethodExists = true
+			}
+			return g.GetActualExpr(fun, errMethodExists)
 		}
 	}
 	return nil

testdata/src/a/issue-173/issue173.go

@@ -0,0 +1,25 @@
+package issue_173
+
+import (
+	"errors"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func intErrFunc() (int, error) {
+	return 42, nil
+}
+
+func strErr() (string, error) {
+	return "", errors.New("error")
+}
+
+var _ = Describe("test if issue 173 was solved", func() {
+	It("should respect the Error() method", func() {
+		Expect(intErrFunc()).Error().To(BeNil()) // want `ginkgo-linter: wrong error assertion. Consider using .Expect\(intErrFunc\(\)\)\.Error\(\)\.ToNot\(HaveOccurred\(\)\). instead`
+		Expect(intErrFunc()).Error().ToNot(HaveOccurred())
+		Expect(intErrFunc()).Error().ToNot(Succeed())
+		Expect(strErr()).Error().To(MatchError(ContainSubstring("error")))
+	})
+})