Merge pull request #2 from utgwkk/generator-better-error-message

generator: better error message

generator/fixtures/ng/invalid_expr/prog.go

@@ -0,0 +1,5 @@
+package invalidexpr
+
+var Iset = []any{
+	1,
+}

generator/fixtures/ng/no_mock_set/prog.go

@@ -0,0 +1 @@
+package foo

generator/fixtures/ng/not_a_new_function/prog.go

@@ -0,0 +1,9 @@
+package foo
+
+var Iset = []any{
+	f(2),
+}
+
+func f(x int) int {
+	return x + 1
+}

generator/fixtures/ng/not_a_slice/prog.go

@@ -0,0 +1,3 @@
+package notaslice
+
+var Iset = 1

generator/fixtures/ng/not_an_interface/prog.go

@@ -0,0 +1,5 @@
+package foo
+
+var Iset = []any{
+	new(*error),
+}

generator/generator.go

@@ -79,7 +79,7 @@ func (g *Generator) findMockSetFromDirectory(sourceDir string) ([]string, error)
 	}
 	for _, p := range parsed {
 		for _, f := range p.Files {
-			mockSet, err := lookupFromScope(f.Scope, g.MockSetName)
+			mockSet, err := lookupFromScope(fset, f.Scope, g.MockSetName)
 			if err != nil {
 				if errors.Is(err, errMockSetNotFound) {
 					continue
@@ -95,7 +95,7 @@ func (g *Generator) findMockSetFromDirectory(sourceDir string) ([]string, error)
 
 var errMockSetNotFound = errors.New("mock set notfound")
 
-func lookupFromScope(s *ast.Scope, mockSetName string) ([]string, error) {
+func lookupFromScope(fset *token.FileSet, s *ast.Scope, mockSetName string) ([]string, error) {
 	obj := s.Lookup(mockSetName)
 	if obj == nil {
 		return nil, errMockSetNotFound
@@ -112,34 +112,39 @@ func lookupFromScope(s *ast.Scope, mockSetName string) ([]string, error) {
 	for _, v := range vs.Values {
 		cmp, ok := v.(*ast.CompositeLit)
 		if !ok {
-			return nil, errors.New("not a interface slice")
+			return nil, newInvalidMockSetError("mock set is not a slice", fset, v)
 		}
 		for _, v := range cmp.Elts {
 			funCall, ok := v.(*ast.CallExpr)
 			if !ok {
-				return nil, errors.New("invalid mock set (contains non-new(...) expression)")
+				return nil, newInvalidMockSetError("mock set contains not a function call", fset, v)
 			}
 			// new(...)
 			newIdent, ok := funCall.Fun.(*ast.Ident)
 			if !ok {
-				return nil, errors.New("invalid mock set (contains non-new(...) expression)")
+				return nil, newInvalidMockSetError("mock set contains not a new(...) function call", fset, v)
 			}
 			if newIdent.Name != "new" {
-				return nil, errors.New("invalid mock set (contains non-new(...) expression)")
+				return nil, newInvalidMockSetError("mock set contains not a new(...) function call", fset, v)
 			}
 			if len(funCall.Args) != 1 {
-				return nil, errors.New("invalid mock set (contains non-new(...) expression)")
+				return nil, newInvalidMockSetError("mock set contains not a new(...) function call", fset, v)
 			}
 			arg := funCall.Args[0]
 			argIdent, ok := arg.(*ast.Ident)
 			if !ok {
-				return nil, errors.New("invalid mock set (contains non-new(...) expression)")
+				return nil, newInvalidMockSetError("not an interface is passed to new(...) function call", fset, arg)
 			}
 			if len(funCall.Args) != 1 {
-				return nil, errors.New("invalid mock set (contains non-new(...) expression)")
+				return nil, newInvalidMockSetError("mock set contains not a new(...) function call", fset, v)
 			}
 			mockSet = append(mockSet, argIdent.Name)
 		}
 	}
 	return mockSet, nil
 }
+
+func newInvalidMockSetError(msg string, fset *token.FileSet, e ast.Expr) error {
+	pos := fset.Position(e.Pos())
+	return fmt.Errorf("%s at file %s, line %d, column %d", msg, pos.Filename, pos.Line, pos.Column)
+}

generator/generator_test.go

@@ -2,6 +2,9 @@ package generator
 
 import (
 	"context"
+	"go/ast"
+	"go/parser"
+	"go/token"
 	"os"
 	"testing"
 
@@ -78,3 +81,62 @@ func TestGenerate(t *testing.T) {
 		})
 	}
 }
+
+func prepareScope(t *testing.T, file string) (*token.FileSet, *ast.Scope) {
+	t.Helper()
+
+	fset := token.NewFileSet()
+	parsed, err := parser.ParseFile(fset, file, nil, 0)
+	require.NoError(t, err)
+
+	return fset, parsed.Scope
+}
+
+func TestLookupFromScope(t *testing.T) {
+	testcases := []struct {
+		name             string
+		inputFile        string
+		inputMockSetName string
+		wantErrMsg       string
+	}{
+		{
+			name:             "not found",
+			inputFile:        "./fixtures/ng/no_mock_set/prog.go",
+			inputMockSetName: "NotFound",
+			wantErrMsg:       "mock set notfound",
+		},
+		{
+			name:             "invalid expression",
+			inputFile:        "./fixtures/ng/invalid_expr/prog.go",
+			inputMockSetName: "Iset",
+			wantErrMsg:       "mock set contains not a function call at file ./fixtures/ng/invalid_expr/prog.go, line 4, column 2",
+		},
+		{
+			name:             "not a new function call",
+			inputFile:        "./fixtures/ng/not_a_new_function/prog.go",
+			inputMockSetName: "Iset",
+			wantErrMsg:       "mock set contains not a new(...) function call at file ./fixtures/ng/not_a_new_function/prog.go, line 4, column 2",
+		},
+		{
+			name:             "new takes not an interface",
+			inputFile:        "./fixtures/ng/not_an_interface/prog.go",
+			inputMockSetName: "Iset",
+			wantErrMsg:       "not an interface is passed to new(...) function call at file ./fixtures/ng/not_an_interface/prog.go, line 4, column 6",
+		},
+		{
+			name:             "not a slice",
+			inputFile:        "./fixtures/ng/not_a_slice/prog.go",
+			inputMockSetName: "Iset",
+			wantErrMsg:       "mock set is not a slice at file ./fixtures/ng/not_a_slice/prog.go, line 3, column 12",
+		},
+	}
+	for _, tc := range testcases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			fset, s := prepareScope(t, tc.inputFile)
+			_, err := lookupFromScope(fset, s, tc.inputMockSetName)
+			require.Error(t, err)
+			assert.Equal(t, tc.wantErrMsg, err.Error())
+		})
+	}
+}