@@ -23,6 +23,7 @@ ruleTester.run("no-useless-echo", rule as never, {
 		"x=$(echo foo | tr a-z A-Z)",
 		"x=$(echo foo; echo bar)",
 		"x=$(echo foo > file)",
+		"x=$(! echo foo)",
 	],
 	invalid: [
 		{
Original file line number	Diff line number	Diff line change
`@@ -23,6 +23,7 @@ ruleTester.run("no-useless-echo", rule as never, {`
`23`	`23`	`"x=$(echo foo \| tr a-z A-Z)",`
`24`	`24`	`"x=$(echo foo; echo bar)",`
`25`	`25`	`"x=$(echo foo > file)",`
	`26`	`+ "x=$(! echo foo)",`
`26`	`27`	`],`
`27`	`28`	`invalid: [`
`28`	`29`	`{`