add line numbers for parser errors (#7326)

parser/parser.go

@@ -65,9 +65,22 @@ var (
 	errInvalidCommand     = errors.New("command must be one of \"from\", \"license\", \"template\", \"system\", \"adapter\", \"parameter\", or \"message\"")
 )
 
+type ParserError struct {
+	LineNumber int
+	Msg        string
+}
+
+func (e *ParserError) Error() string {
+	if e.LineNumber > 0 {
+		return fmt.Sprintf("(line %d): %s", e.LineNumber, e.Msg)
+	}
+	return e.Msg
+}
+
 func ParseFile(r io.Reader) (*File, error) {
 	var cmd Command
 	var curr state
+	var currLine int = 1
 	var b bytes.Buffer
 	var role string
 
@@ -84,11 +97,18 @@ func ParseFile(r io.Reader) (*File, error) {
 			return nil, err
 		}
 
+		if isNewline(r) {
+			currLine++
+		}
+
 		next, r, err := parseRuneForState(r, curr)
 		if errors.Is(err, io.ErrUnexpectedEOF) {
 			return nil, fmt.Errorf("%w: %s", err, b.String())
 		} else if err != nil {
-			return nil, err
+			return nil, &ParserError{
+				LineNumber: currLine,
+				Msg:        err.Error(),
+			}
 		}
 
 		// process the state transition, some transitions need to be intercepted and redirected
@@ -96,7 +116,10 @@ func ParseFile(r io.Reader) (*File, error) {
 			switch curr {
 			case stateName:
 				if !isValidCommand(b.String()) {
-					return nil, errInvalidCommand
+					return nil, &ParserError{
+						LineNumber: currLine,
+						Msg:        errInvalidCommand.Error(),
+					}
 				}
 
 				// next state sometimes depends on the current buffer value
@@ -117,7 +140,10 @@ func ParseFile(r io.Reader) (*File, error) {
 				cmd.Name = b.String()
 			case stateMessage:
 				if !isValidMessageRole(b.String()) {
-					return nil, errInvalidMessageRole
+					return nil, &ParserError{
+						LineNumber: currLine,
+						Msg:        errInvalidMessageRole.Error(),
+					}
 				}
 
 				role = b.String()

parser/parser_test.go

@@ -3,6 +3,7 @@ package parser
 import (
 	"bytes"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"io"
 	"strings"
@@ -180,8 +181,15 @@ func TestParseFileBadCommand(t *testing.T) {
 FROM foo
 BADCOMMAND param1 value1
 `
+	parserError := &ParserError{
+		LineNumber: 3,
+		Msg:        errInvalidCommand.Error(),
+	}
+
 	_, err := ParseFile(strings.NewReader(input))
-	require.ErrorIs(t, err, errInvalidCommand)
+	if !errors.As(err, &parserError) {
+		t.Errorf("unexpected error: expected: %s, actual: %s", parserError.Error(), err.Error())
+	}
 }
 
 func TestParseFileMessages(t *testing.T) {
@@ -245,7 +253,10 @@ FROM foo
 MESSAGE badguy I'm a bad guy!
 `,
 			nil,
-			errInvalidMessageRole,
+			&ParserError{
+				LineNumber: 3,
+				Msg:        errInvalidMessageRole.Error(),
+			},
 		},
 		{
 			`
@@ -264,13 +275,35 @@ MESSAGE system`,
 		},
 	}
 
-	for _, c := range cases {
+	for _, tt := range cases {
 		t.Run("", func(t *testing.T) {
-			modelfile, err := ParseFile(strings.NewReader(c.input))
-			require.ErrorIs(t, err, c.err)
+			modelfile, err := ParseFile(strings.NewReader(tt.input))
+
 			if modelfile != nil {
-				assert.Equal(t, c.expected, modelfile.Commands)
+				assert.Equal(t, tt.expected, modelfile.Commands)
+			}
+
+			if tt.err == nil {
+				if err != nil {
+					t.Fatalf("expected no error, but got %v", err)
+				}
+				return
+			}
+
+			switch tt.err.(type) {
+			case *ParserError:
+				var pErr *ParserError
+				if errors.As(err, &pErr) {
+					// got the correct type of error
+					return
+				}
+			}
+
+			if errors.Is(err, tt.err) {
+				return
 			}
+
+			t.Fatalf("unexpected error: expected: %v, actual: %v", tt.err, err)
 		})
 	}
 }