add class JavaScannerTest

core-java/src/test/java/org/baeldung/java/io/JavaScannerTest.java

@@ -0,0 +1,184 @@
+package org.baeldung.java.io;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+import java.io.BufferedReader;
+import java.io.ByteArrayInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Scanner;
+
+import org.junit.Test;
+
+public class JavaScannerTest {
+
+    @Test
+    public void whenReadFileWithScanner_thenCorrect() throws IOException {
+        final Scanner scanner = new Scanner(new File("src/test/resources/test_read.in"));
+
+        assertTrue(scanner.hasNext());
+        assertEquals("Hello", scanner.next());
+        assertEquals("world", scanner.next());
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenConvertInputStreamToString_thenConverted() throws IOException {
+        final String expectedValue = "Hello world";
+        final FileInputStream inputStream = new FileInputStream("src/test/resources/test_read.in");
+        final Scanner scanner = new Scanner(inputStream);
+        scanner.useDelimiter("\\A");
+
+        final String result = scanner.next();
+        assertEquals(expectedValue, result);
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenReadUsingBufferedReader_thenCorrect() throws IOException {
+        final String firstLine = "Hello world";
+        final String secondLine = "Hi, John";
+        final BufferedReader reader = new BufferedReader(new FileReader("src/test/resources/test_read_multiple.in"));
+
+        String result = reader.readLine();
+        assertEquals(firstLine, result);
+
+        result = reader.readLine();
+        assertEquals(secondLine, result);
+
+        reader.close();
+    }
+
+    @Test
+    public void whenReadUsingScanner_thenCorrect() throws IOException {
+        final String firstLine = "Hello world";
+        final FileInputStream inputStream = new FileInputStream("src/test/resources/test_read_multiple.in");
+        final Scanner scanner = new Scanner(inputStream);
+
+        final String result = scanner.nextLine();
+        assertEquals(firstLine, result);
+
+        scanner.useDelimiter(", ");
+        assertEquals("Hi", scanner.next());
+        assertEquals("John", scanner.next());
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenReadInputFromConsole_thenCorrect() {
+        final String input = "Hello";
+        final InputStream stdin = System.in;
+        System.setIn(new ByteArrayInputStream(input.getBytes()));
+
+        final Scanner scanner = new Scanner(System.in);
+        final String result = scanner.next();
+        assertEquals(input, result);
+
+        System.setIn(stdin);
+        scanner.close();
+    }
+
+    @Test
+    public void whenValidateInputUsingScanner_thenValidated() throws IOException {
+        final String input = "2000";
+        final InputStream stdin = System.in;
+        System.setIn(new ByteArrayInputStream(input.getBytes()));
+
+        final Scanner scanner = new Scanner(System.in);
+
+        final boolean isIntInput = scanner.hasNextInt();
+        assertTrue(isIntInput);
+
+        System.setIn(stdin);
+        scanner.close();
+    }
+
+    @Test
+    public void whenScanString_thenCorrect() throws IOException {
+        final String input = "Hello 1 F 3.5";
+        final Scanner scanner = new Scanner(input);
+
+        assertEquals("Hello", scanner.next());
+        assertEquals(1, scanner.nextInt());
+        assertEquals(15, scanner.nextInt(16));
+        assertEquals(3.5, scanner.nextDouble(), 0.00000001);
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenFindPatternUsingScanner_thenFound() throws IOException {
+        final String expectedValue = "world";
+        final FileInputStream inputStream = new FileInputStream("src/test/resources/test_read.in");
+        final Scanner scanner = new Scanner(inputStream);
+
+        final String result = scanner.findInLine("wo..d");
+        assertEquals(expectedValue, result);
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenFindPatternInHorizon_thenFound() throws IOException {
+        final String expectedValue = "world";
+        final FileInputStream inputStream = new FileInputStream("src/test/resources/test_read.in");
+        final Scanner scanner = new Scanner(inputStream);
+
+        String result = scanner.findWithinHorizon("wo..d", 5);
+        assertNull(result);
+
+        result = scanner.findWithinHorizon("wo..d", 100);
+        assertEquals(expectedValue, result);
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenSkipPatternUsingScanner_thenSkiped() throws IOException {
+        final FileInputStream inputStream = new FileInputStream("src/test/resources/test_read.in");
+        final Scanner scanner = new Scanner(inputStream);
+
+        scanner.skip(".e.lo");
+
+        assertEquals("world", scanner.next());
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenChangeScannerDelimiter_thenChanged() throws IOException {
+        final String expectedValue = "Hello world";
+        final String[] splited = expectedValue.split("o");
+
+        final FileInputStream inputStream = new FileInputStream("src/test/resources/test_read.in");
+        final Scanner scanner = new Scanner(inputStream);
+        scanner.useDelimiter("o");
+
+        assertEquals(splited[0], scanner.next());
+        assertEquals(splited[1], scanner.next());
+        assertEquals(splited[2], scanner.next());
+
+        scanner.close();
+    }
+
+    @Test
+    public void whenReadWithScannerTwoDelimiters_thenCorrect() throws IOException {
+        final Scanner scanner = new Scanner(new File("src/test/resources/test_read_d.in"));
+        scanner.useDelimiter(",|-");
+
+        assertEquals("John", scanner.next());
+        assertEquals("Adam", scanner.next());
+        assertEquals("Tom", scanner.next());
+
+        scanner.close();
+    }
+
+}

core-java/src/test/resources/test_read_d.in

@@ -0,0 +1 @@
+John,Adam-Tom

core-java/src/test/resources/test_read_multiple.in

@@ -0,0 +1,2 @@
+Hello world
+Hi, John