BAEL-6812 Test Main Method with JUnit

- added sample to test main method with different architecture
2023-08-25 20:12:50 +03:00
parent 63033cd8cf
commit fd6b6aa6d5
12 changed files with 460 additions and 0 deletions
@@ -0,0 +1,100 @@
+package com.baeldung.junit.main.test;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.PrintStream;
+import java.nio.charset.Charset;
+
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+public class TestSimpleMain {
+    private InputStream defaultIn;
+    private PrintStream defaultOut;
+
+    @BeforeEach
+    public void setUp() {
+        defaultIn = System.in;
+        defaultOut = System.out;
+    }
+
+    @AfterEach
+    public void tearDown() {
+        System.setIn(defaultIn);
+        System.setOut(defaultOut);
+    }
+
+    @Test
+    public void givenArgumentAsConsoleInput_WhenReadFromSubstitutedByteStream_ThenSuccessfullyCalculate() throws IOException {
+        String[] arguments = new String[] { "-i", "CONSOLE" };
+
+        final InputStream fips = new ByteArrayInputStream("1 2 3".getBytes());
+        final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        final PrintStream out = new PrintStream(byteArrayOutputStream);
+
+        System.setIn(fips);
+        System.setOut(out);
+
+        //execute
+        SimpleMain.main(arguments);
+
+        //verify
+        String consoleOutput = byteArrayOutputStream.toString(Charset.defaultCharset());
+        assertTrue(consoleOutput.contains("Calculated sum: 6"));
+
+        fips.close();
+        out.close();
+    }
+
+    @Test
+    public void givenArgumentAsConsoleInput_WhenReadFromSubstitutedFileStream_ThenSuccessfullyCalculate() throws IOException {
+        String[] arguments = new String[] { "-i", "CONSOLE" };
+
+        final InputStream fips = getClass().getClassLoader()
+            .getResourceAsStream("test-input.txt");
+        final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        final PrintStream out = new PrintStream(byteArrayOutputStream);
+
+        System.setIn(fips);
+        System.setOut(out);
+
+        //execute
+        SimpleMain.main(arguments);
+
+        //verify
+        String consoleOutput = byteArrayOutputStream.toString(Charset.defaultCharset());
+        assertTrue(consoleOutput.contains("Calculated sum: 10"));
+
+        fips.close();
+        out.close();
+    }
+
+    @Test
+    public void givenLongArgumentAsConsoleInput_WhenReadFromSubstitutedFileStream_ThenSuccessfullyCalculate() throws IOException {
+        String[] arguments = new String[] { "--input", "CONSOLE" };
+
+        final InputStream fips = getClass().getClassLoader()
+            .getResourceAsStream("test-input.txt");
+        final ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
+        final PrintStream out = new PrintStream(byteArrayOutputStream);
+
+        System.setIn(fips);
+        System.setOut(out);
+
+        //execute
+        SimpleMain.main(arguments);
+
+        //verify
+        String consoleOutput = byteArrayOutputStream.toString(Charset.defaultCharset());
+        assertTrue(consoleOutput.contains("Calculated sum: 10"));
+
+        fips.close();
+        out.close();
+    }
+
+}
@@ -0,0 +1,37 @@
+package com.baeldung.junit.main.test;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
+
+public class TestStaticMain {
+
+    @Test
+    public void givenArgumentAsConsoleInput_WhenReadFromSubstitutedByteArrayInputStream_ThenSuccessfullyCalculate() throws IOException {
+        String[] arguments = new String[] { "-i", "CONSOLE" };
+        try (MockedStatic<StaticMain> mockedStatic = Mockito.mockStatic(StaticMain.class, Mockito.CALLS_REAL_METHODS);
+            InputStream fips = new ByteArrayInputStream("1 2 3".getBytes())) {
+
+            final InputStream original = System.in;
+
+            //Reassigns the "standard" input stream
+            System.setIn(fips);
+
+            ArgumentCaptor<String> stringArgumentCaptor = ArgumentCaptor.forClass(String.class);
+
+            //execute
+            StaticMain.main(arguments);
+
+            //verify
+            mockedStatic.verify(() -> StaticMain.calculateSum(stringArgumentCaptor.capture()));
+
+            System.setIn(original);
+        }
+    }
+
+}
@@ -0,0 +1 @@
+4 5 1