feat: add test file

CS2030STest.java

@@ -0,0 +1,77 @@
+import java.net.URI;
+import java.util.List;
+import javax.tools.DiagnosticCollector;
+import javax.tools.SimpleJavaFileObject;
+import javax.tools.ToolProvider;
+
+class CS2030STest {
+
+  public static final String ANSI_RESET = "\u001B[0m";
+  public static final String ANSI_RED = "\u001B[31m";
+  public static final String ANSI_GREEN = "\u001B[32m";
+
+  /**
+   * Test if two objects are equals.
+   *
+   * @param test A description of the test.
+   * @param output The output from an expression.
+   * @param expect The expected output from that expression.
+   * @return this object.
+   */
+  public CS2030STest expect(String test, Object output, Object expect) {
+    System.out.print(test);
+    if ((expect == null && output == null) || output.equals(expect)) {
+      System.out.println(".. " + ANSI_GREEN + "ok" + ANSI_RESET);
+    } else {
+      System.out.println(".. " + ANSI_RED + "failed" + ANSI_RESET);
+      System.out.println("  expected: " + expect);
+      System.out.println("  got this: " + output);
+    }
+    return this;
+  }
+
+  /**
+   * Test if an expression compiles with/without error.
+   *
+   * @param test A description of the test.
+   * @param statement The java statement to compile
+   * @param success Whether the statement is expected to compile or not 
+   *     (true if yes; false otherwise)
+   * @return this object.
+   */
+  public CS2030STest expectCompile(String test, String statement, boolean success) {
+    System.out.print(test);
+
+    class JavaSourceFromString extends SimpleJavaFileObject {
+      final String code;
+
+      JavaSourceFromString(String code) {
+        super(URI.create("string:///TempClass.java"), Kind.SOURCE);
+        this.code = "class TempClass {void foo(){" +  code + ";}}";
+      }
+
+      @Override
+      public CharSequence getCharContent(boolean ignoreEncodingErrors) {
+        return code;
+      }
+    }
+
+    boolean noError = ToolProvider
+        .getSystemJavaCompiler()
+        .getTask(null, null, new DiagnosticCollector<>(), null, null, 
+            List.of(new JavaSourceFromString(statement)))
+        .call();
+
+    if (noError != success) {
+      System.out.println(".. " + ANSI_RED + "failed" + ANSI_RESET);
+      if (!success) {
+        System.out.println("  expected compilation error but it compiles fine.");
+      } else {
+        System.out.println("  expected the statement to compile without errors but it does not.");
+      }
+    } else {
+      System.out.println(".. " + ANSI_GREEN + "ok" + ANSI_RESET);
+    }
+    return this;
+  }
+}