package com.example;

import org.junit.jupiter.api.DynamicTest;
import org.junit.jupiter.api.TestFactory;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;
import java.util.Map;
import java.util.stream.Stream;

import static org.junit.jupiter.api.Assertions.fail;
import static org.junit.jupiter.api.DynamicTest.dynamicTest;

public class MainTest {

    @TestFactory
    Stream<DynamicTest> testPrintDayMessage() {
        Map<Integer, String> dayToExpected = Map.of(
                1, "monday",
                2, "tuesday",
                3, "wednesday",
                4, "thursday",
                5, "friday",
                6, "saturday",
                7, "sunday",
                0, "invalid",
                99, "invalid"
        );

        return dayToExpected.entrySet().stream().map(entry -> {
            int input = entry.getKey();
            String expectedSubstring = entry.getValue().toLowerCase();

            ByteArrayOutputStream outContent = new ByteArrayOutputStream();
            PrintStream originalOut = System.out;
            System.setOut(new PrintStream(outContent));

            Main.printDayMessage(input);

            System.setOut(originalOut);

            String actualOutput = outContent.toString().trim().toLowerCase();
            boolean passed = actualOutput.contains(expectedSubstring);

            String displayName = passed
                    ? "Day " + input + " output contains: '" + expectedSubstring + "'"
                    : "Day " + input + " output missing expected text: '" + expectedSubstring + "'";

            return dynamicTest(displayName, () -> {
                if (!passed) {
                    fail("Expected output to contain: '" + expectedSubstring + "' but got: '" + actualOutput + "'");
                }
            });
        });
    }
}

MainTest.java

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