Utils

Author: krotname

pom.xml

@@ -17,7 +17,6 @@
                     <source>21</source>
                     <target>17</target>
                     <release>17</release>
-                    <compilerArgs>--enable-preview</compilerArgs>
                 </configuration>
             </plugin>
         </plugins>

src/main/java/algorithms/sprint0/Utils.java

@@ -1,19 +1,23 @@
 package algorithms.sprint0;
 
-import lombok.experimental.UtilityClass;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import org.junit.jupiter.api.Test;
 
-import java.io.BufferedReader;
-import java.io.IOException;
-import java.io.Writer;
+import java.io.*;
 import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 
-@UtilityClass
+import static org.junit.jupiter.api.Assertions.*;
+
+@NoArgsConstructor(access = AccessLevel.PUBLIC)
 public class Utils {
 
     public static List<Integer> readList(BufferedReader reader) throws IOException {
-        return Arrays.stream(reader.readLine().trim().split("\\s+"))
+        String line = reader.readLine();
+        if (line == null) throw new NumberFormatException("EOF");
+        return Arrays.stream(line.trim().split("\\s+"))
                 .map(Integer::parseInt)
                 .collect(Collectors.toList());
     }
@@ -29,6 +33,118 @@ public static <T> void printList(List<T> list, Writer writer) {
     }
 
     public static int readInt(BufferedReader reader) throws IOException {
-        return Integer.parseInt(reader.readLine());
+        String line = reader.readLine();
+        if (line == null) throw new NumberFormatException("EOF");
+        return Integer.parseInt(line);
+    }
+
+    @Test
+    public void readListbasic() throws Exception {
+        BufferedReader br = new BufferedReader(new StringReader("1 2 3"));
+        List<Integer> got = readList(br);
+        assertEquals(Arrays.asList(1, 2, 3), got);
+    }
+
+    @Test
+    void readList_mixedWhitespace_and_signs() throws Exception {
+        BufferedReader br = new BufferedReader(new StringReader("  -1\t0   5  "));
+        List<Integer> got = readList(br);
+        assertEquals(Arrays.asList(-1, 0, 5), got);
+    }
+
+    @Test
+    void readList_emptyLine_throwsNumberFormat() {
+        BufferedReader br = new BufferedReader(new StringReader("\\n"));
+        assertThrows(NumberFormatException.class, () -> readList(br));
+    }
+
+    @Test
+    void readList_EOF_throwsNumberFormat() {
+        BufferedReader br = new BufferedReader(new StringReader(""));
+        assertThrows(NumberFormatException.class, () -> readList(br));
+    }
+
+    @Test
+    void readList_nonIntegerToken_throwsNumberFormat() {
+        BufferedReader br = new BufferedReader(new StringReader("1 a 3"));
+        assertThrows(NumberFormatException.class, () -> readList(br));
+    }
+
+    @Test
+    void readList_overflow_throwsNumberFormat() {
+        BufferedReader br = new BufferedReader(new StringReader("2147483648"));
+        assertThrows(NumberFormatException.class, () -> readList(br));
+    }
+
+    // --- readInt ---
+
+    @Test
+    void readInt_basic() throws Exception {
+        BufferedReader br = new BufferedReader(new StringReader("42"));
+        assertEquals(42, readInt(br));
+    }
+
+    @Test
+    void readInt_negative() throws Exception {
+        BufferedReader br = new BufferedReader(new StringReader("-7"));
+        assertEquals(-7, readInt(br));
+    }
+
+    @Test
+    void readInt_withSpaces_throwsNumberFormat() {
+        BufferedReader br = new BufferedReader(new StringReader(" 42 "));
+        assertThrows(NumberFormatException.class, () -> readInt(br));
+    }
+
+    // --- printList ---
+
+    @Test
+    void printList_integers_trailingSpace_noNewline() throws Exception {
+        StringWriter sw = new StringWriter();
+        printList(Arrays.asList(1, 2, 3), sw);
+        assertEquals("1 2 3 ", sw.toString());
+    }
+
+    @Test
+    void printList_strings_usesToString() throws Exception {
+        StringWriter sw = new StringWriter();
+        printList(Arrays.asList("a", "b"), sw);
+        assertEquals("a b ", sw.toString());
+    }
+
+    @Test
+    void printList_empty_writesNothing() throws Exception {
+        StringWriter sw = new StringWriter();
+        printList(List.of(), sw);
+        assertEquals("", sw.toString());
+    }
+
+    @Test
+    void printList_ioExceptions_areSwallowed() {
+        Writer throwing = new Writer() {
+            @Override
+            public void write(char[] cbuf, int off, int len) throws IOException {
+                throw new IOException("boom");
+            }
+
+            @Override
+            public void flush() {
+            }
+
+            @Override
+            public void close() {
+            }
+
+            @Override
+            public void write(String str) throws IOException {
+                throw new IOException("boom");
+            }
+
+            @Override
+            public void write(int c) throws IOException {
+                throw new IOException("boom");
+            }
+        };
+        assertDoesNotThrow(() -> printList(Arrays.asList(1, 2, 3), throwing));
     }
 }