Added tests for interpreter pattern

interpreter/src/test/java/com/iluwatar/interpreter/ExpressionTest.java

@@ -0,0 +1,111 @@
+package com.iluwatar.interpreter;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.function.BiFunction;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+/**
+ * Date: 12/14/15 - 11:48 AM
+ *
+ * @author Jeroen Meulemeester
+ */
+public abstract class ExpressionTest<E extends Expression> {
+
+  /**
+   * Generate inputs ranging from -10 to 10 for both input params and calculate the expected result
+   *
+   * @param resultCalc The function used to calculate the expected result
+   * @return A data set with test entries
+   */
+  static List<Object[]> prepareParameters(final BiFunction<Integer, Integer, Integer> resultCalc) {
+    final List<Object[]> testData = new ArrayList<>();
+    for (int i = -10; i < 10; i++) {
+      for (int j = -10; j < 10; j++) {
+        testData.add(new Object[]{
+                new NumberExpression(i),
+                new NumberExpression(j),
+                resultCalc.apply(i, j)
+        });
+      }
+    }
+    return testData;
+  }
+
+  /**
+   * The input used as first parameter during the test
+   */
+  private final NumberExpression first;
+
+  /**
+   * The input used as second parameter during the test
+   */
+  private final NumberExpression second;
+
+  /**
+   * The expected result of the calculation, taking the first and second parameter in account
+   */
+  private final int result;
+
+  /**
+   * The expected {@link E#toString()} response
+   */
+  private final String expectedToString;
+
+  /**
+   * Factory, used to create a new test object instance with the correct first and second parameter
+   */
+  private final BiFunction<NumberExpression, NumberExpression, E> factory;
+
+  /**
+   * Create a new test instance with the given parameters and expected results
+   *
+   * @param first            The input used as first parameter during the test
+   * @param second           The input used as second parameter during the test
+   * @param result           The expected result of the tested expression
+   * @param expectedToString The expected {@link E#toString()} response
+   * @param factory          Factory, used to create a new test object instance
+   */
+  ExpressionTest(final NumberExpression first, final NumberExpression second, final int result,
+                 final String expectedToString, final BiFunction<NumberExpression, NumberExpression, E> factory) {
+
+    this.first = first;
+    this.second = second;
+    this.result = result;
+    this.expectedToString = expectedToString;
+    this.factory = factory;
+  }
+
+  /**
+   * Get the first parameter
+   *
+   * @return The first parameter
+   */
+  final NumberExpression getFirst() {
+    return this.first;
+  }
+
+  /**
+   * Verify if the expression calculates the correct result when calling {@link E#interpret()}
+   */
+  @Test
+  public void testInterpret() {
+    final E expression = this.factory.apply(this.first, this.second);
+    assertNotNull(expression);
+    assertEquals(this.result, expression.interpret());
+  }
+
+  /**
+   * Verify if the expression has the expected {@link E#toString()} value
+   */
+  @Test
+  public void testToString() {
+    final E expression = this.factory.apply(this.first, this.second);
+    assertNotNull(expression);
+    assertEquals(expectedToString, expression.toString());
+  }
+}

interpreter/src/test/java/com/iluwatar/interpreter/MinusExpressionTest.java

@@ -0,0 +1,38 @@
+package com.iluwatar.interpreter;
+
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+import java.util.List;
+
+/**
+ * Date: 12/14/15 - 12:08 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+@RunWith(Parameterized.class)
+public class MinusExpressionTest extends ExpressionTest<MinusExpression> {
+
+  /**
+   * Create a new set of test entries with the expected result
+   *
+   * @return The list of parameters used during this test
+   */
+  @Parameters
+  public static List<Object[]> data() {
+    return prepareParameters((f, s) -> f - s);
+  }
+
+  /**
+   * Create a new test instance using the given test parameters and expected result
+   *
+   * @param first  The first expression parameter
+   * @param second The second expression parameter
+   * @param result The expected result
+   */
+  public MinusExpressionTest(final NumberExpression first, final NumberExpression second, final int result) {
+    super(first, second, result, "-", MinusExpression::new);
+  }
+
+}

interpreter/src/test/java/com/iluwatar/interpreter/MultiplyExpressionTest.java

@@ -0,0 +1,38 @@
+package com.iluwatar.interpreter;
+
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+import java.util.List;
+
+/**
+ * Date: 12/14/15 - 12:08 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+@RunWith(Parameterized.class)
+public class MultiplyExpressionTest extends ExpressionTest<MultiplyExpression> {
+
+  /**
+   * Create a new set of test entries with the expected result
+   *
+   * @return The list of parameters used during this test
+   */
+  @Parameters
+  public static List<Object[]> data() {
+    return prepareParameters((f, s) -> f * s);
+  }
+
+  /**
+   * Create a new test instance using the given test parameters and expected result
+   *
+   * @param first  The first expression parameter
+   * @param second The second expression parameter
+   * @param result The expected result
+   */
+  public MultiplyExpressionTest(final NumberExpression first, final NumberExpression second, final int result) {
+    super(first, second, result, "*", MultiplyExpression::new);
+  }
+
+}

interpreter/src/test/java/com/iluwatar/interpreter/NumberExpressionTest.java

@@ -0,0 +1,52 @@
+package com.iluwatar.interpreter;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Date: 12/14/15 - 12:08 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+@RunWith(Parameterized.class)
+public class NumberExpressionTest extends ExpressionTest<NumberExpression> {
+
+  /**
+   * Create a new set of test entries with the expected result
+   *
+   * @return The list of parameters used during this test
+   */
+  @Parameters
+  public static List<Object[]> data() {
+    return prepareParameters((f, s) -> f);
+  }
+
+  /**
+   * Create a new test instance using the given test parameters and expected result
+   *
+   * @param first  The first expression parameter
+   * @param second The second expression parameter
+   * @param result The expected result
+   */
+  public NumberExpressionTest(final NumberExpression first, final NumberExpression second, final int result) {
+    super(first, second, result, "number", (f, s) -> f);
+  }
+
+  /**
+   * Verify if the {@link NumberExpression#NumberExpression(String)} constructor works as expected
+   */
+  @Test
+  public void testFromString() throws Exception {
+    final int expectedValue = getFirst().interpret();
+    final String testStingValue = String.valueOf(expectedValue);
+    final NumberExpression numberExpression = new NumberExpression(testStingValue);
+    assertEquals(expectedValue, numberExpression.interpret());
+  }
+
+}

interpreter/src/test/java/com/iluwatar/interpreter/PlusExpressionTest.java

@@ -0,0 +1,38 @@
+package com.iluwatar.interpreter;
+
+import org.junit.runner.RunWith;
+import org.junit.runners.Parameterized;
+import org.junit.runners.Parameterized.Parameters;
+
+import java.util.List;
+
+/**
+ * Date: 12/14/15 - 12:08 PM
+ *
+ * @author Jeroen Meulemeester
+ */
+@RunWith(Parameterized.class)
+public class PlusExpressionTest extends ExpressionTest<PlusExpression> {
+
+  /**
+   * Create a new set of test entries with the expected result
+   *
+   * @return The list of parameters used during this test
+   */
+  @Parameters
+  public static List<Object[]> data() {
+    return prepareParameters((f, s) -> f + s);
+  }
+
+  /**
+   * Create a new test instance using the given test parameters and expected result
+   *
+   * @param first  The first expression parameter
+   * @param second The second expression parameter
+   * @param result The expected result
+   */
+  public PlusExpressionTest(final NumberExpression first, final NumberExpression second, final int result) {
+    super(first, second, result, "+", PlusExpression::new);
+  }
+
+}