--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/main/java/fj/test/CheckResult.java	Fri Mar 20 21:04:03 2015 +0900
@@ -0,0 +1,299 @@
+package fj.test;
+
+import static fj.Bottom.decons;
+import fj.F;
+import fj.Show;
+import fj.data.List;
+import fj.data.Option;
+import static fj.data.Option.some;
+import static fj.Show.listShow;
+import static fj.Show.showS;
+import static fj.test.Arg.argShow;
+
+import java.io.StringWriter;
+import java.io.PrintWriter;
+
+/**
+ * An enumeration of the possible results after checking a property. A <code>CheckResult</code> may
+ * be in one of six states:
+ * <ol>
+ * <li>Passed</li>
+ * <li>Proven</li>
+ * <li>Falsified</li>
+ * <li>Exhausted</li>
+ * <li>Exception executing the property</li>
+ * <li>Exception generating values to check the property</li>
+ * </ol>
+ *
+ * @version %build.number%
+ */
+public final class CheckResult {
+  private final R r;
+  private final Option<List<Arg<?>>> args;
+  private final Option<Throwable> ex;
+  private final int succeeded;
+  private final int discarded;
+
+  private enum R {
+    Passed, Proven, Falsified, Exhausted, PropException, GenException
+  }
+
+  private CheckResult(final R r, final Option<List<Arg<?>>> args, final Option<Throwable> ex, final int succeeded,
+                      final int discarded) {
+    this.r = r;
+    this.args = args;
+    this.ex = ex;
+    this.succeeded = succeeded;
+    this.discarded = discarded;
+  }
+
+  /**
+   * Returns a result that the property has passed.
+   *
+   * @param succeeded The number of checks that succeeded.
+   * @param discarded The number of checks that were discarded.
+   * @return A result that the property has passed.
+   */
+  public static CheckResult passed(final int succeeded, final int discarded) {
+    return new CheckResult(R.Passed, Option.<List<Arg<?>>>none(), Option.<Throwable>none(), succeeded, discarded);
+  }
+
+  /**
+   * Returns a result that the property has been proven.
+   *
+   * @param args      The arguments used to prove the property.
+   * @param succeeded The number of checks that succeeded.
+   * @param discarded The number of checks that were discarded.
+   * @return A result that the property has been proven.
+   */
+  public static CheckResult proven(final List<Arg<?>> args, final int succeeded, final int discarded) {
+    return new CheckResult(R.Proven, some(args), Option.<Throwable>none(), succeeded, discarded);
+  }
+
+  /**
+   * Returns a result that the property has been falsified.
+   *
+   * @param args      The arguments used to falsify the property.
+   * @param succeeded The number of checks that succeeded.
+   * @param discarded The number of checks that were discarded.
+   * @return A result that the property has been falsified.
+   */
+  public static CheckResult falsified(final List<Arg<?>> args, final int succeeded, final int discarded) {
+    return new CheckResult(R.Falsified, some(args), Option.<Throwable>none(), succeeded, discarded);
+  }
+
+  /**
+   * Returns a result that the property been exhausted in checking.
+   *
+   * @param succeeded The number of checks that succeeded.
+   * @param discarded The number of checks that were discarded.
+   * @return A result that the property has been exhausted in checking.
+   */
+  public static CheckResult exhausted(final int succeeded, final int discarded) {
+    return new CheckResult(R.Exhausted, Option.<List<Arg<?>>>none(), Option.<Throwable>none(), succeeded, discarded);
+  }
+
+  /**
+   * Returns a result that checking the property threw an exception.
+   *
+   * @param args      The arguments used when the exception was thrown.
+   * @param ex        The exception that was thrown.
+   * @param succeeded The number of checks that succeeded.
+   * @param discarded The number of checks that were discarded.
+   * @return A result that checking the property threw an exception.
+   */
+  public static CheckResult propException(final List<Arg<?>> args, final Throwable ex, final int succeeded,
+                                          final int discarded) {
+    return new CheckResult(R.PropException, some(args), some(ex), succeeded, discarded);
+  }
+
+
+  /**
+   * Returns a result that generating values to check the property threw an exception.
+   *
+   * @param ex        The exception that was thrown.
+   * @param succeeded The number of checks that succeeded.
+   * @param discarded The number of checks that were discarded.
+   * @return A result that generating values to check the property threw an exception.
+   */
+  public static CheckResult genException(final Throwable ex, final int succeeded, final int discarded) {
+    return new CheckResult(R.GenException, Option.<List<Arg<?>>>none(), some(ex), succeeded, discarded);
+  }
+
+  /**
+   * Returns <code>true</code> if this result is passed, <code>false</code> otherwise.
+   *
+   * @return <code>true</code> if this result is passed, <code>false</code> otherwise.
+   */
+  public boolean isPassed() {
+    return r == R.Passed;
+  }
+
+  /**
+   * Returns <code>true</code> if this result is proven, <code>false</code> otherwise.
+   *
+   * @return <code>true</code> if this result is proven, <code>false</code> otherwise.
+   */
+  public boolean isProven() {
+    return r == R.Proven;
+  }
+
+  /**
+   * Returns <code>true</code> if this result is falsified, <code>false</code> otherwise.
+   *
+   * @return <code>true</code> if this result is falsified, <code>false</code> otherwise.
+   */
+  public boolean isFalsified() {
+    return r == R.Falsified;
+  }
+
+  /**
+   * Returns <code>true</code> if this result is exhausted, <code>false</code> otherwise.
+   *
+   * @return <code>true</code> if this result is exhausted, <code>false</code> otherwise.
+   */
+  public boolean isExhausted() {
+    return r == R.Exhausted;
+  }
+
+
+  /**
+   * Returns <code>true</code> if this result is an exception during property execution,
+   * <code>false</code> otherwise.
+   *
+   * @return <code>true</code> if this result is an exception during property execution,
+   *         <code>false</code> otherwise.
+   */
+  public boolean isPropException() {
+    return r == R.PropException;
+  }
+
+  /**
+   * Returns <code>true</code> if this result is an exception during generating of values for
+   * property checking, <code>false</code> otherwise.
+   *
+   * @return <code>true</code> if this result is an exception during generating of values for
+   *         property checking, <code>false</code> otherwise.
+   */
+  public boolean isGenException() {
+    return r == R.GenException;
+  }
+
+  /**
+   * Returns the arguments if the result is one of; proven, falsified or exception during property
+   * execution, otherwise, no arguments are returned.
+   *
+   * @return The arguments if the result is one of; proven, falsified or exception during property
+   *         execution, otherwise, no arguments are returned.
+   */
+  public Option<List<Arg<?>>> args() {
+    return args;
+  }
+
+  /**
+   * Returns the execption if the result is one of; exception during property execution or exception
+   * during argument value generation, otherwise, no exception are returned.
+   *
+   * @return The execption if the result is one of; exception during property execution or exception
+   *         during argument value generation, otherwise, no exception are returned.
+   */
+  public Option<Throwable> exception() {
+    return ex;
+  }
+
+  /**
+   * Returns the number of succeeded checks of the property in this result.
+   *
+   * @return The number of succeeded checks of the property in this result.
+   */
+  public int succeeded() {
+    return succeeded;
+  }
+
+  /**
+   * Returns the number of discarded checks of the property in this result.
+   *
+   * @return The number of discarded checks of the property in this result.
+   */
+  public int discarded() {
+    return discarded;
+  }
+
+  /**
+   * A rendering of a check result that summarises in one line.
+   *
+   * @param sa The rendering of arguments.
+   * @return A rendering of a check result that summarises in one line.
+   */
+  public static Show<CheckResult> summary(final Show<Arg<?>> sa) {
+    return showS(new F<CheckResult, String>() {
+      private String test(final CheckResult r) {
+        return r.succeeded() == 1 ? "test" : "tests";
+      }
+
+      private String arguments(final CheckResult r) {
+        final List<Arg<?>> args = r.args().some();
+        return args.length() == 1 ? "argument: " + sa.showS(args.head()) : "arguments: " + listShow(sa).showS(args);
+      }
+
+      @SuppressWarnings({"ThrowableResultOfMethodCallIgnored"})
+      public String f(final CheckResult r) {
+        if (r.isProven())
+          return "OK, property proven with " + arguments(r);
+        else if (r.isPassed())
+          return "OK, passed " + r.succeeded() + ' ' + test(r) +
+              (r.discarded() > 0 ? " (" + r.discarded() + " discarded)" : "") + '.';
+        else if (r.isFalsified())
+          return "Falsified after " + r.succeeded() + " passed " + test(r) + " with " + arguments(r);
+        else if (r.isExhausted())
+          return "Gave up after " + r.succeeded() + " passed " + test(r) + " and " + r.discarded() +
+              " discarded tests.";
+        else if (r.isPropException()) {
+          final StringWriter sw = new StringWriter();
+          final PrintWriter pw = new PrintWriter(sw);
+          r.exception().some().printStackTrace(pw);
+          return "Exception on property evaluation with " + arguments(r) + System.getProperty("line.separator") + sw;
+        } else if (r.isGenException()) {
+          final StringWriter sw = new StringWriter();
+          final PrintWriter pw = new PrintWriter(sw);
+          r.exception().some().printStackTrace(pw);
+          return "Exception on argument generation " + System.getProperty("line.separator") + sw;
+        } else
+          throw decons(r.getClass());
+      }
+    });
+  }
+
+  /**
+   * A rendering of a check result that summarises in one line.
+   */
+  public static final Show<CheckResult> summary = summary(argShow);
+
+  /**
+   * A rendering of a check result that summarises in one line but throws an exception in the result
+   * is a failure (falsified, property exception or generator exception).
+   */
+  public static final Show<CheckResult> summaryEx = summaryEx(argShow);
+
+  /**
+   * A rendering of a check result that summarises in one line but throws an exception in the result
+   * is a failure (falsified, property exception or generator exception).
+   *
+   * @param sa The rendering of arguments.
+   * @return A rendering of a check result that summarises in one line but throws an exception in
+   *         the result is a failure (falsified, property exception or generator exception).
+   */
+  public static Show<CheckResult> summaryEx(final Show<Arg<?>> sa) {
+    return showS(new F<CheckResult, String>() {
+      public String f(final CheckResult r) {
+        final String s = summary(sa).show(r).toString();
+        if (r.isProven() || r.isPassed() || r.isExhausted())
+          return s;
+        else if (r.isFalsified() || r.isPropException() || r.isGenException())
+          throw new Error(s);
+        else
+          throw decons(r.getClass());
+      }
+    });
+  }
+}