catching wrong path in JUnit - junit

Question

import org.junit.Test;
import org.junit.Assert;
import org.junit.Assert.*;
import java.io.FileNotFoundException;
ChartIO io = new ChartIO();
#Test
public void test_readFile_SadPath() {
String path="abc.txt";
try {
io.readFile(path);
}catch(Exception ex) {
assertTrue(ex instanceof FileNotFoundException );
}
}
I want to create a test case for below code but it gives always this error
cannot find symbol
[ERROR] symbol: method assertTrue(boolean)
[ERROR] location: class demo.junit_class_demo.grades.ChartIOTest
public int[] readFile(String filepath) {
List<Integer> linesList = new ArrayList<>();
try (BufferedReader reader = new BufferedReader(new FileReader(filepath))) {
String line;
while ((line = reader.readLine()) != null) {
linesList.add(Integer.parseInt(line));
}
} catch (FileNotFoundException e) {
throw new IllegalArgumentException("File " + filepath + " does not exist");
} catch (IOException e) {
throw new NumberFormatException();
}
int[] linesArray = new int[linesList.size()];
for (int index = 0; index < linesList.size(); index++) {
linesArray[index] = linesList.get(index);
}
return linesArray;
}
Where is my mistake?
Whole error lines:
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] /home/X/Desktop/Y/Z/A/project/unit_test_demo/src/test/java/grades/ChartIOTest.java:[22,25] cannot find symbol
symbol: method assertTrue(boolean)
location: class demo.junit_class_demo.grades.ChartIOTest
[INFO] 1 error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.787 s
[INFO] Finished at: 2020-03-16T18:04:35+03:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:testCompile (default-testCompile) on project 481.demo.child: Compilation failure
[ERROR] /home/Z/Desktop/X/Y/K/project/unit_test_demo/src/test/java/grades/ChartIOTest.java:[22,25] cannot find symbol
[ERROR] symbol: method assertTrue(boolean)
[ERROR] location: class demo.junit_class_demo.grades.ChartIOTest
[ERROR]
[ERROR] -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoFailureException
This is whole error lines.