Add string tests ... (#27)

- String API
- String Comparison
- Escape Sequences
- String Formatting

Author: mperor

basics/src/test/java/pl/mperor/lab/java/ConsoleSupportTest.java

@@ -0,0 +1,28 @@
+package pl.mperor.lab.java;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.io.ByteArrayInputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Scanner;
+
+public class ConsoleSupportTest {
+
+    @Test
+    public void testSimulatedSystemInScanner() {
+        byte[] bytes = """
+                Hello
+                World""".getBytes(StandardCharsets.UTF_8);
+
+        var original = System.in;
+        System.setIn(new ByteArrayInputStream(bytes));
+
+        try (Scanner sc = new Scanner(System.in)) {
+            Assertions.assertEquals("Hello", sc.next());
+            Assertions.assertEquals("World", sc.next());
+        }
+        System.setIn(original);
+    }
+
+}

basics/src/test/java/pl/mperor/lab/java/data/type/NumberSystemsTest.java

@@ -3,39 +3,37 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
-import java.util.regex.Pattern;
-
 public class NumberSystemsTest {
 
     @Test
     public void testBinary() {
         String raw = "1011";
         int radix = 2;
-        Assertions.assertTrue(Pattern.compile("[01]+").asMatchPredicate().test(raw));
+        Assertions.assertTrue(raw.matches("[01]+"));
         Assertions.assertEquals(0b1011, Integer.parseInt(raw, radix));
     }
 
     @Test
     public void testOctal() {
         String raw = "13";
         int radix = 8;
-        Assertions.assertTrue(Pattern.compile("[0-7]+").asMatchPredicate().test(raw));
+        Assertions.assertTrue(raw.matches("[0-7]+"));
         Assertions.assertEquals(013, Integer.parseInt(raw, radix));
     }
 
     @Test
     public void testHex() {
         String raw = "1a";
         int radix = 16;
-        Assertions.assertTrue(Pattern.compile("[0-9A-Fa-f]+").asMatchPredicate().test(raw));
+        Assertions.assertTrue(raw.matches("[0-9A-Fa-f]+"));
         Assertions.assertEquals(0x1a, Integer.parseInt(raw, radix));
     }
 
     @Test
     public void testDecimal() {
         String raw = "111";
         int radix = 10;
-        Assertions.assertTrue(Pattern.compile("[0-9]+").asMatchPredicate().test(raw));
+        Assertions.assertTrue(raw.matches("[0-9]+"));
         Assertions.assertEquals(111, Integer.parseInt(raw, radix));
     }
 

basics/src/test/java/pl/mperor/lab/java/data/type/StringTest.java

@@ -0,0 +1,70 @@
+package pl.mperor.lab.java.data.type;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Locale;
+
+public class StringTest {
+
+    @Test
+    public void testStringCommonlyUsedMethods() {
+        String abc = "abc";
+        Assertions.assertEquals(3, abc.length());
+        Assertions.assertTrue(abc.contains("b"));
+        Assertions.assertTrue(!abc.isBlank() && !abc.isEmpty());
+        Assertions.assertTrue(abc.startsWith("a") && abc.endsWith("c"));
+        Assertions.assertEquals("a*c", abc.replace('b', '*'));
+        Assertions.assertEquals("bc", abc.substring(1, abc.length()));
+        Assertions.assertArrayEquals(new String[]{"google", "com"}, "google.com".split("\\."));
+        Assertions.assertTrue("-1".matches("^-?\\d+$"), "Like isInteger(...)");
+    }
+
+    @Test
+    public void testStringImmutability() {
+        String original = "| Fix";
+        String modified = original
+                .replace('|', ' ')
+                .strip()
+                .concat("ed")
+                .toUpperCase();
+
+        Assertions.assertEquals("| Fix", original);
+        Assertions.assertEquals("FIXED", modified);
+    }
+
+    @Test
+    public void testCompareStrings() {
+        String qwerty = "qwerty";
+        String newQwerty = new String(qwerty);
+        Assertions.assertTrue("qwerty" == qwerty, "String Pool exits!");
+        Assertions.assertFalse(qwerty == newQwerty);
+        Assertions.assertTrue(qwerty == newQwerty.intern(), "'intern()' returns string from the pool");
+        Assertions.assertTrue(qwerty.equals(newQwerty));
+        Assertions.assertTrue(qwerty.equalsIgnoreCase("Qwerty"));
+    }
+
+    @Test
+    public void testEscapeSequences() {
+        String doubleQuote = "\"Title\"";
+        String tabulator = "\tabc";
+        String backslash = "C:\\Windows";
+        String newLine = "...\n***";
+        String carriageReturn = "[          ] 0%\r[==========] 100%";
+        String unicodeCode = "Copyright \u00A9";
+        List.of(doubleQuote, tabulator, backslash, newLine, carriageReturn, unicodeCode)
+                .forEach(System.out::println);
+    }
+
+    @Test
+    public void testStringFormatting() {
+        // Format specifier: %[flags][width][.precision]conversion
+        // Escaping %%
+        String format = "%s | %d | %#x | %.2f | %b | %c | %% |%n";
+        String formatted = String.format(Locale.UK, format, "Str", 1, 10, 1.23, true, '.');
+        var separator = System.getProperty("line.separator");
+        Assertions.assertEquals("Str | 1 | 0xa | 1.23 | true | . | % |" + separator, formatted);
+    }
+
+}

jdk/src/test/java/pl/mperor/lab/java/Java4.java

@@ -51,7 +51,6 @@ public void testRegex() {
 
     private String getTestHtml() {
         return """
-                \
                 <!DOCTYPE html>
                     <html lang="en">
                     <head>