Add fsext.Abs helper function (#3452)

js/initcontext.go

@@ -4,7 +4,6 @@ import (
 	"errors"
 	"fmt"
 	"net/url"
-	"path/filepath"
 
 	"github.com/dop251/goja"
 	"github.com/sirupsen/logrus"
@@ -20,20 +19,7 @@ const cantBeUsedOutsideInitContextMsg = `the "%s" function is only available in
 // contents of a file. If the second argument is "b" it returns an ArrayBuffer
 // instance, otherwise a string representation.
 func openImpl(rt *goja.Runtime, fs fsext.Fs, basePWD *url.URL, filename string, args ...string) (goja.Value, error) {
-	// Here IsAbs should be enough but unfortunately it doesn't handle absolute paths starting from
-	// the current drive on windows like `\users\noname\...`. Also it makes it more easy to test and
-	// will probably be need for archive execution under windows if always consider '/...' as an
-	// absolute path.
-	if filename[0] != '/' && filename[0] != '\\' && !filepath.IsAbs(filename) {
-		filename = filepath.Join(basePWD.Path, filename)
-	}
-	filename = filepath.Clean(filename)
-
-	if filename[0:1] != fsext.FilePathSeparator {
-		filename = fsext.FilePathSeparator + filename
-	}
-
-	data, err := readFile(fs, filename)
+	data, err := readFile(fs, fsext.Abs(basePWD.Path, filename))
 	if err != nil {
 		return nil, err
 	}

lib/fsext/filepath.go

@@ -15,3 +15,31 @@ import (
 func JoinFilePath(b, p string) string {
 	return filepath.Join(b, filepath.Clean("/"+p))
 }
+
+// Abs returns an absolute representation of path.
+//
+// this implementation allows k6 to handle absolute paths starting from
+// the current drive on windows like `\users\noname\...`. It makes it easier
+// to test and is needed for archive execution under windows (it always consider '/...' as an
+// absolute path).
+//
+// If the path is not absolute it will be joined with root
+// to turn it into an absolute path. The root path is assumed
+// to be a directory.
+//
+// Because k6 does not interact with the OS itself, but with
+// its own virtual file system, it needs to be able to resolve
+// the root path of the file system. In most cases this would be
+// the bundle or init environment's working directory.
+func Abs(root, path string) string {
+	if path[0] != '/' && path[0] != '\\' && !filepath.IsAbs(path) {
+		path = filepath.Join(root, path)
+	}
+	path = filepath.Clean(path)
+
+	if path[0:1] != FilePathSeparator {
+		path = FilePathSeparator + path
+	}
+
+	return path
+}

lib/fsext/filepath_unix_test.go

@@ -72,3 +72,59 @@ func TestJoinFilePath(t *testing.T) {
 		})
 	}
 }
+
+func TestAbs(t *testing.T) {
+	t.Parallel()
+
+	type args struct {
+		root string
+		path string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "absolute path",
+			args: args{
+				root: "/",
+				path: "/test",
+			},
+			want: "/test",
+		},
+		{
+			name: "relative path",
+			args: args{
+				root: "/",
+				path: "test",
+			},
+			want: "/test",
+		},
+		{
+			name: "relative path with leading dot",
+			args: args{
+				root: "/",
+				path: "./test",
+			},
+			want: "/test",
+		},
+		{
+			name: "relative path with leading double dot",
+			args: args{
+				root: "/",
+				path: "../test",
+			},
+			want: "/test",
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			assert.Equal(t, tt.want, fsext.Abs(tt.args.root, tt.args.path))
+		})
+	}
+}

lib/fsext/filepath_windows_test.go

@@ -64,3 +64,59 @@ func TestJoinFilePath(t *testing.T) {
 		})
 	}
 }
+
+func TestAbs(t *testing.T) {
+	t.Parallel()
+
+	type args struct {
+		root string
+		path string
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "absolute path",
+			args: args{
+				root: "\\",
+				path: "\\test",
+			},
+			want: "\\test",
+		},
+		{
+			name: "relative path",
+			args: args{
+				root: "\\",
+				path: "test",
+			},
+			want: "\\test",
+		},
+		{
+			name: "relative path with leading dot",
+			args: args{
+				root: "\\",
+				path: ".\\test",
+			},
+			want: "\\test",
+		},
+		{
+			name: "relative path with leading double dot",
+			args: args{
+				root: "\\",
+				path: "..\\test",
+			},
+			want: "\\test",
+		},
+	}
+	for _, tt := range tests {
+		tt := tt
+
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			assert.Equal(t, tt.want, fsext.Abs(tt.args.root, tt.args.path))
+		})
+	}
+}