Added TierConstraint and MeteredConstraint

Change-Id: Iadc50c98dc0ba7092313f880df8055ab0e401c29
diff --git a/core/api/src/main/java/org/onosproject/net/intent/constraint/MeteredConstraint.java b/core/api/src/main/java/org/onosproject/net/intent/constraint/MeteredConstraint.java
new file mode 100644
index 0000000..584cd99
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/intent/constraint/MeteredConstraint.java
@@ -0,0 +1,98 @@
+/*
+ * Copyright 2014-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.net.intent.constraint;
+
+import com.google.common.annotations.Beta;
+import org.onosproject.net.AnnotationKeys;
+import org.onosproject.net.Link;
+import org.onosproject.net.intent.ResourceContext;
+
+import java.util.Objects;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+
+/**
+ * Constraint that evaluates links based on the metered flag.
+ */
+@Beta
+public class MeteredConstraint extends BooleanConstraint {
+
+    private final boolean useMetered;
+
+    /**
+     * Creates a new constraint for requesting connectivity using or avoiding
+     * the metered links.
+     *
+     * @param metered   indicates whether a metered link can be used.
+     */
+    public MeteredConstraint(boolean metered) {
+        this.useMetered = metered;
+    }
+
+    // Constructor for serialization
+    private MeteredConstraint() {
+        this.useMetered = false;
+    }
+
+    // doesn't use LinkResourceService
+    @Override
+    public boolean isValid(Link link, ResourceContext context) {
+        // explicitly call a method not depending on LinkResourceService
+        return isValid(link);
+    }
+
+    private boolean isValid(Link link) {
+        return !isMeteredLink(link) || useMetered;
+    }
+
+    private boolean isMeteredLink(Link link) {
+        return link.annotations().keys().contains(AnnotationKeys.METERED)
+                && Boolean.valueOf(link.annotations().value(AnnotationKeys.METERED));
+    }
+
+    /**
+     * Indicates if the constraint is metered or not.
+     *
+     * @return true if metered
+     */
+    public boolean isUseMetered() {
+        return useMetered;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(useMetered);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null || getClass() != obj.getClass()) {
+            return false;
+        }
+        final MeteredConstraint other = (MeteredConstraint) obj;
+        return Objects.equals(this.useMetered, other.useMetered);
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("metered", useMetered)
+                .toString();
+    }
+}
diff --git a/core/api/src/main/java/org/onosproject/net/intent/constraint/TierConstraint.java b/core/api/src/main/java/org/onosproject/net/intent/constraint/TierConstraint.java
new file mode 100644
index 0000000..37e5776
--- /dev/null
+++ b/core/api/src/main/java/org/onosproject/net/intent/constraint/TierConstraint.java
@@ -0,0 +1,188 @@
+/*
+ * Copyright 2014-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.net.intent.constraint;
+
+import com.google.common.annotations.Beta;
+import com.google.common.collect.ImmutableSet;
+import org.onosproject.net.AnnotationKeys;
+import org.onosproject.net.Link;
+import org.onosproject.net.intent.ResourceContext;
+
+import java.util.Objects;
+import java.util.List;
+
+import static com.google.common.base.MoreObjects.toStringHelper;
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Constraint that evaluates links based on their type.
+ */
+@Beta
+public class TierConstraint extends BooleanConstraint {
+
+    public enum CostType {
+        /**
+         * Configures the constraint to return the same cost (1.0) for any
+         * link that has a valid tier value.
+         */
+        VALID,
+        /**
+         * Configures the constraint to return the tier value as the cost.
+         */
+        TIER,
+        /**
+         * Configures the constraint to return the order the tier value was
+         * added to the list of included tiers on the constraint.
+         */
+        ORDER;
+    }
+
+    private final List<Integer> tiers;
+    private final boolean isInclusive;
+    private final CostType costType;
+
+    /**
+     * Creates a new constraint for requesting connectivity using or avoiding
+     * the specified link tiers.
+     *
+     * @param inclusive indicates whether the given link tiers are to be
+     *                  permitted or avoided
+     * @param costType  defines the model used to calculate the link cost.
+     * @param tiers     link tiers
+     */
+    public TierConstraint(boolean inclusive, CostType costType, Integer... tiers) {
+        checkNotNull(tiers, "Link tiers cannot be null");
+        checkArgument(tiers.length > 0, "There must at least one tier");
+        if (costType == CostType.ORDER) {
+            checkArgument(inclusive, "Order is only valid when inclusive=true");
+        }
+        this.tiers = ImmutableSet.copyOf(tiers).asList();
+        this.isInclusive = inclusive;
+        this.costType = costType;
+    }
+
+    /**
+     * Creates a new constraint for requesting connectivity using or avoiding
+     * the specified link tiers. The VALID cost type is used by default.
+     *
+     * @param inclusive indicates whether the given link tiers are to be
+     *                  permitted or avoided
+     * @param tiers     link tiers
+     */
+    public TierConstraint(boolean inclusive, Integer... tiers) {
+        this(inclusive, CostType.VALID, tiers);
+    }
+
+    // Constructor for serialization
+    private TierConstraint() {
+        this.tiers = null;
+        this.isInclusive = false;
+        this.costType = CostType.VALID;
+    }
+
+    // doesn't use LinkResourceService
+    @Override
+    public boolean isValid(Link link, ResourceContext context) {
+        // explicitly call a method not depending on LinkResourceService
+        return isValid(link);
+    }
+
+    private boolean isValid(Link link) {
+        boolean contains = link.annotations().keys().contains(AnnotationKeys.TIER)
+                            && tiers.contains(Integer.valueOf(
+                                   link.annotations().value(AnnotationKeys.TIER)));
+        return isInclusive == contains;
+    }
+
+    // doesn't use LinkResourceService
+    @Override
+    public double cost(Link link, ResourceContext context) {
+        // explicitly call a method not depending on LinkResourceService
+        return cost(link);
+    }
+
+    private double cost(Link link) {
+        double cost = -1.0;
+
+        if (isValid(link)) {
+            Integer tier = new Integer(link.annotations().value(AnnotationKeys.TIER));
+            if (costType == CostType.ORDER) {
+                cost = tiers.indexOf(tier) + 1;
+            } else if (costType == CostType.TIER) {
+                cost = tier;
+            } else {
+                cost = 1.0;
+            }
+        }
+
+        return cost;
+    }
+
+    /**
+     * Returns the set of link tiers.
+     *
+     * @return set of link tiers
+     */
+    public List<Integer> tiers() {
+        return tiers;
+    }
+
+    /**
+     * Indicates if the constraint is inclusive or exclusive.
+     *
+     * @return true if inclusive
+     */
+    public boolean isInclusive() {
+        return isInclusive;
+    }
+
+    /**
+     * Return the cost model used by this constraint.
+     *
+     * @return true if inclusive
+     */
+    public CostType costType() {
+        return costType;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(tiers, isInclusive);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null || getClass() != obj.getClass()) {
+            return false;
+        }
+        final TierConstraint other = (TierConstraint) obj;
+        return Objects.equals(this.tiers, other.tiers) && Objects.equals(this.isInclusive, other.isInclusive)
+                && Objects.equals(this.costType, other.costType);
+    }
+
+    @Override
+    public String toString() {
+        return toStringHelper(this)
+                .add("inclusive", isInclusive)
+                .add("costType", costType)
+                .add("tiers", tiers)
+                .toString();
+    }
+}
diff --git a/core/api/src/test/java/org/onosproject/net/intent/constraint/MeteredConstraintTest.java b/core/api/src/test/java/org/onosproject/net/intent/constraint/MeteredConstraintTest.java
new file mode 100644
index 0000000..9ee145d
--- /dev/null
+++ b/core/api/src/test/java/org/onosproject/net/intent/constraint/MeteredConstraintTest.java
@@ -0,0 +1,194 @@
+/*
+ * Copyright 2014-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.net.intent.constraint;
+
+import com.google.common.testing.EqualsTester;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.graph.ScalarWeight;
+import org.onosproject.net.Annotations;
+import org.onosproject.net.DefaultAnnotations;
+import org.onosproject.net.DefaultLink;
+import org.onosproject.net.DefaultPath;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Link;
+import org.onosproject.net.Path;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.intent.ResourceContext;
+import org.onosproject.net.provider.ProviderId;
+
+import java.util.Arrays;
+
+import static org.easymock.EasyMock.createMock;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+import static org.onosproject.net.AnnotationKeys.METERED;
+import static org.onosproject.net.DefaultLinkTest.cp;
+import static org.onosproject.net.DeviceId.deviceId;
+import static org.onosproject.net.Link.Type.DIRECT;
+
+public class MeteredConstraintTest {
+
+    private static final DeviceId DID1 = deviceId("of:1");
+    private static final DeviceId DID2 = deviceId("of:2");
+    private static final DeviceId DID3 = deviceId("of:3");
+    private static final PortNumber PN1 = PortNumber.portNumber(1);
+    private static final PortNumber PN2 = PortNumber.portNumber(2);
+    private static final PortNumber PN3 = PortNumber.portNumber(3);
+    private static final PortNumber PN4 = PortNumber.portNumber(4);
+    private static final PortNumber PN5 = PortNumber.portNumber(5);
+    private static final PortNumber PN6 = PortNumber.portNumber(6);
+    private static final ProviderId PROVIDER_ID = new ProviderId("of", "foo");
+    private static final String METERED1 = String.valueOf(true);
+    private static final String METERED2 = String.valueOf(false);
+
+    private ResourceContext resourceContext;
+
+    private Path meteredPath;
+    private Path nonMeteredPath;
+    private Link meteredLink;
+    private Link nonMeteredLink;
+    private Link unAnnotatedLink;
+
+    @Before
+    public void setUp() {
+        resourceContext = createMock(ResourceContext.class);
+
+        Annotations annotations1 = DefaultAnnotations.builder().set(METERED, METERED1).build();
+        Annotations annotations2 = DefaultAnnotations.builder().set(METERED, METERED2).build();
+
+        meteredLink = DefaultLink.builder()
+                .providerId(PROVIDER_ID)
+                .src(cp(DID1, PN1))
+                .dst(cp(DID2, PN2))
+                .type(DIRECT)
+                .annotations(annotations1)
+                .build();
+        nonMeteredLink = DefaultLink.builder()
+                .providerId(PROVIDER_ID)
+                .src(cp(DID2, PN3))
+                .dst(cp(DID3, PN4))
+                .type(DIRECT)
+                .annotations(annotations2)
+                .build();
+        unAnnotatedLink = DefaultLink.builder()
+                .providerId(PROVIDER_ID)
+                .src(cp(DID1, PN5))
+                .dst(cp(DID3, PN6))
+                .type(DIRECT)
+                .build();
+        meteredPath = new DefaultPath(PROVIDER_ID, Arrays.asList(meteredLink, nonMeteredLink),
+                ScalarWeight.toWeight(10));
+        nonMeteredPath = new DefaultPath(PROVIDER_ID, Arrays.asList(nonMeteredLink, unAnnotatedLink),
+                ScalarWeight.toWeight(10));
+    }
+
+    /**
+     * Tests the path is valid with a metered link and the supplied constraint.
+     */
+    @Test
+    public void testAllowedOnAllPaths() {
+        MeteredConstraint constraint = new MeteredConstraint(true);
+
+        assertThat(constraint.validate(meteredPath, resourceContext), is(true));
+        assertThat(constraint.validate(nonMeteredPath, resourceContext), is(true));
+    }
+
+    /**
+     * Tests the path is not valid with a metered link and the supplied constraint.
+     */
+    @Test
+    public void tesNotAllowedOntMeteredPath() {
+        MeteredConstraint constraint = new MeteredConstraint(false);
+
+        assertThat(constraint.validate(meteredPath, resourceContext), is(false));
+    }
+
+    /**
+     * Tests the path is not valid with a metered link and the supplied constraint.
+     */
+    @Test
+    public void testNotAllowsOnNonMeteredPath() {
+        MeteredConstraint constraint = new MeteredConstraint(false);
+
+        assertThat(constraint.validate(nonMeteredPath, resourceContext), is(true));
+    }
+
+    /**
+     * Tests that all links are valid for a constraint allowing metered links.
+     */
+    @Test
+    public void testMeteredAllowed() {
+        MeteredConstraint constraint = new MeteredConstraint(true);
+
+        assertThat(constraint.isValid(meteredLink, resourceContext), is(true));
+        assertThat(constraint.isValid(nonMeteredLink, resourceContext), is(true));
+        assertThat(constraint.isValid(unAnnotatedLink, resourceContext), is(true));
+    }
+
+    /**
+     * Tests that only non-metered links are valid for a constraint not allowing metered links.
+     */
+    @Test
+    public void testMeteredNotAllowed() {
+        MeteredConstraint constraint = new MeteredConstraint(false);
+
+        assertThat(constraint.isValid(meteredLink, resourceContext), is(false));
+        assertThat(constraint.isValid(nonMeteredLink, resourceContext), is(true));
+        assertThat(constraint.isValid(unAnnotatedLink, resourceContext), is(true));
+    }
+
+    /**
+     * Tests the link costs for a constraint allowing metered links.
+     */
+    @Test
+    public void testCostAllowed() {
+        MeteredConstraint constraint = new MeteredConstraint(true);
+
+        assertThat(constraint.cost(meteredLink, resourceContext), is(1.0));
+        assertThat(constraint.cost(nonMeteredLink, resourceContext), is(1.0));
+        assertThat(constraint.cost(unAnnotatedLink, resourceContext), is(1.0));
+    }
+
+    /**
+     * Tests the link costs for a constraint not allowing metered links.
+     */
+    @Test
+    public void testCostNotAllowed() {
+        MeteredConstraint constraint = new MeteredConstraint(false);
+
+        assertThat(constraint.cost(meteredLink, resourceContext), is(-1.0));
+        assertThat(constraint.cost(nonMeteredLink, resourceContext), is(1.0));
+        assertThat(constraint.cost(unAnnotatedLink, resourceContext), is(1.0));
+    }
+
+    /**
+     * Tests equality of the constraint instances.
+     */
+    @Test
+    public void testEquality() {
+        MeteredConstraint c1 = new MeteredConstraint(true);
+        MeteredConstraint c2 = new MeteredConstraint(true);
+
+        MeteredConstraint c3 = new MeteredConstraint(false);
+        MeteredConstraint c4 = new MeteredConstraint(false);
+
+        new EqualsTester()
+                .addEqualityGroup(c1, c2)
+                .addEqualityGroup(c3, c4)
+                .testEquals();
+    }
+}
diff --git a/core/api/src/test/java/org/onosproject/net/intent/constraint/TierConstraintTest.java b/core/api/src/test/java/org/onosproject/net/intent/constraint/TierConstraintTest.java
new file mode 100644
index 0000000..5a48d87
--- /dev/null
+++ b/core/api/src/test/java/org/onosproject/net/intent/constraint/TierConstraintTest.java
@@ -0,0 +1,252 @@
+/*
+ * Copyright 2014-present Open Networking Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.net.intent.constraint;
+
+import com.google.common.testing.EqualsTester;
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.graph.ScalarWeight;
+import org.onosproject.net.Annotations;
+import org.onosproject.net.DefaultAnnotations;
+import org.onosproject.net.DefaultLink;
+import org.onosproject.net.DefaultPath;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.Path;
+import org.onosproject.net.PortNumber;
+import org.onosproject.net.intent.Constraint;
+import org.onosproject.net.intent.ResourceContext;
+import org.onosproject.net.provider.ProviderId;
+
+import java.util.Arrays;
+
+import static org.easymock.EasyMock.createMock;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+import static org.onosproject.net.AnnotationKeys.TIER;
+import static org.onosproject.net.DefaultLinkTest.cp;
+import static org.onosproject.net.DeviceId.deviceId;
+import static org.onosproject.net.Link.Type.DIRECT;
+
+/**
+ * Test for constraint of intermediate elements.
+ */
+public class TierConstraintTest {
+
+    private static final DeviceId DID1 = deviceId("of:1");
+    private static final DeviceId DID2 = deviceId("of:2");
+    private static final DeviceId DID3 = deviceId("of:3");
+    private static final DeviceId DID4 = deviceId("of:4");
+    private static final PortNumber PN1 = PortNumber.portNumber(1);
+    private static final PortNumber PN2 = PortNumber.portNumber(2);
+    private static final PortNumber PN3 = PortNumber.portNumber(3);
+    private static final PortNumber PN4 = PortNumber.portNumber(4);
+    private static final PortNumber PN5 = PortNumber.portNumber(5);
+    private static final PortNumber PN6 = PortNumber.portNumber(6);
+    private static final ProviderId PROVIDER_ID = new ProviderId("of", "foo");
+    private static final String TIER1 = "1";
+    private static final String TIER2 = "2";
+    private static final String TIER3 = "3";
+
+    private ResourceContext resourceContext;
+
+    private Path path12;
+    private Path path13;
+    private Path path23;
+    private DefaultLink link1;
+    private DefaultLink link2;
+    private DefaultLink link3;
+
+    @Before
+    public void setUp() {
+        resourceContext = createMock(ResourceContext.class);
+
+        Annotations annotations1 = DefaultAnnotations.builder().set(TIER, TIER1).build();
+        Annotations annotations2 = DefaultAnnotations.builder().set(TIER, TIER2).build();
+        Annotations annotations3 = DefaultAnnotations.builder().set(TIER, TIER3).build();
+
+        link1 = DefaultLink.builder()
+                .providerId(PROVIDER_ID)
+                .src(cp(DID1, PN1))
+                .dst(cp(DID2, PN2))
+                .type(DIRECT)
+                .annotations(annotations1)
+                .build();
+        link2 = DefaultLink.builder()
+                .providerId(PROVIDER_ID)
+                .src(cp(DID2, PN3))
+                .dst(cp(DID3, PN4))
+                .type(DIRECT)
+                .annotations(annotations2)
+                .build();
+        link3 = DefaultLink.builder()
+                .providerId(PROVIDER_ID)
+                .src(cp(DID2, PN5))
+                .dst(cp(DID4, PN6))
+                .type(DIRECT)
+                .annotations(annotations3)
+                .build();
+
+        path12 = new DefaultPath(PROVIDER_ID, Arrays.asList(link1, link2), ScalarWeight.toWeight(10));
+        path13 = new DefaultPath(PROVIDER_ID, Arrays.asList(link1, link3), ScalarWeight.toWeight(10));
+        path23 = new DefaultPath(PROVIDER_ID, Arrays.asList(link2, link3), ScalarWeight.toWeight(10));
+    }
+
+    /**
+     * Tests that all of the links in the specified path have a tier included in the specified included tiers.
+     */
+    @Test
+    public void testSatisfyIncludedTiers() {
+        TierConstraint constraint12 = new TierConstraint(true, 1, 2);
+        assertThat(constraint12.validate(path12, resourceContext), is(true));
+
+        TierConstraint constraint13 = new TierConstraint(true, 1, 3);
+        assertThat(constraint13.validate(path13, resourceContext), is(true));
+
+        TierConstraint constraint23 = new TierConstraint(true, 2, 3);
+        assertThat(constraint23.validate(path23, resourceContext), is(true));
+    }
+
+    /**
+     * Tests that at least one link in the specified path has a tier not included the specified included tiers.
+     */
+    @Test
+    public void testNotSatisfyIncludedTiers() {
+        TierConstraint constraint12 = new TierConstraint(true, 1, 2);
+        assertThat(constraint12.validate(path13, resourceContext), is(false));
+        assertThat(constraint12.validate(path23, resourceContext), is(false));
+
+        TierConstraint constraint13 = new TierConstraint(true, 1, 3);
+        assertThat(constraint13.validate(path12, resourceContext), is(false));
+        assertThat(constraint13.validate(path23, resourceContext), is(false));
+
+        TierConstraint constraint23 = new TierConstraint(true, 2, 3);
+        assertThat(constraint23.validate(path12, resourceContext), is(false));
+        assertThat(constraint23.validate(path13, resourceContext), is(false));
+    }
+
+    /**
+     * Tests that all of the links in the specified path do not have a tier in the specified excluded tiers.
+     */
+    @Test
+    public void testSatisfyExcludedTiers() {
+        TierConstraint constraint12 = new TierConstraint(false, 1);
+        assertThat(constraint12.validate(path23, resourceContext), is(true));
+
+        TierConstraint constraint13 = new TierConstraint(false, 2);
+        assertThat(constraint13.validate(path13, resourceContext), is(true));
+
+        TierConstraint constraint23 = new TierConstraint(false, 3);
+        assertThat(constraint23.validate(path12, resourceContext), is(true));
+    }
+
+    /**
+     * Tests that at least one link in the specified path has a tier in the specified excluded tiers.
+     */
+    @Test
+    public void testNotSatisfyExcludedTiers() {
+        TierConstraint constraint12 = new TierConstraint(false, 1);
+        assertThat(constraint12.validate(path12, resourceContext), is(false));
+        assertThat(constraint12.validate(path13, resourceContext), is(false));
+
+        TierConstraint constraint13 = new TierConstraint(false, 2);
+        assertThat(constraint13.validate(path12, resourceContext), is(false));
+        assertThat(constraint13.validate(path23, resourceContext), is(false));
+
+        TierConstraint constraint23 = new TierConstraint(false, 3);
+        assertThat(constraint23.validate(path13, resourceContext), is(false));
+        assertThat(constraint23.validate(path23, resourceContext), is(false));
+    }
+
+    /**
+     * Tests the link cost is equal to order in which a tier was added to the constraint.
+     */
+    @Test
+    public void testOrderCost() {
+        TierConstraint constraint32 = new TierConstraint(true, TierConstraint.CostType.ORDER, 3, 2);
+
+        assertThat(constraint32.cost(link1, resourceContext), is(-1.0));
+        assertThat(constraint32.cost(link2, resourceContext), is(2.0));
+        assertThat(constraint32.cost(link3, resourceContext), is(1.0));
+
+        TierConstraint constraint123 = new TierConstraint(true, TierConstraint.CostType.ORDER, 1, 2, 3);
+
+        assertThat(constraint123.cost(link1, resourceContext), is(1.0));
+        assertThat(constraint123.cost(link2, resourceContext), is(2.0));
+        assertThat(constraint123.cost(link3, resourceContext), is(3.0));
+
+        TierConstraint constraint231 = new TierConstraint(true, TierConstraint.CostType.ORDER, 2, 3, 1);
+
+        assertThat(constraint231.cost(link1, resourceContext), is(3.0));
+        assertThat(constraint231.cost(link2, resourceContext), is(1.0));
+        assertThat(constraint231.cost(link3, resourceContext), is(2.0));
+
+        TierConstraint constraint312 = new TierConstraint(true, TierConstraint.CostType.ORDER, 3, 1, 2);
+
+        assertThat(constraint312.cost(link1, resourceContext), is(2.0));
+        assertThat(constraint312.cost(link2, resourceContext), is(3.0));
+        assertThat(constraint312.cost(link3, resourceContext), is(1.0));
+    }
+
+    /**
+     * Tests the link cost is equal to order in which a tier was added to the constraint.
+     */
+    @Test
+    public void testOrderCostWithDuplicates() {
+        TierConstraint constraint32 = new TierConstraint(true, TierConstraint.CostType.ORDER, 3, 2, 1, 1, 2, 3);
+
+        assertThat(constraint32.cost(link1, resourceContext), is(3.0));
+        assertThat(constraint32.cost(link2, resourceContext), is(2.0));
+        assertThat(constraint32.cost(link3, resourceContext), is(1.0));
+    }
+
+    /**
+     * Tests the link cost is equal to tier value.
+     */
+    @Test
+    public void testTierCost() {
+        TierConstraint constraint123 = new TierConstraint(true, TierConstraint.CostType.TIER, 3, 1);
+
+        assertThat(constraint123.cost(link1, resourceContext), is(1.0));
+        assertThat(constraint123.cost(link2, resourceContext), is(-1.0));
+        assertThat(constraint123.cost(link3, resourceContext), is(3.0));
+    }
+
+    /**
+     * Tests the link cost is 1 if valid and -1 if invalid.
+     */
+    @Test
+    public void testValidCost() {
+        TierConstraint constraint = new TierConstraint(true, TierConstraint.CostType.VALID, 2, 1);
+
+        assertThat(constraint.cost(link1, resourceContext), is(1.0));
+        assertThat(constraint.cost(link2, resourceContext), is(1.0));
+        assertThat(constraint.cost(link3, resourceContext), is(-1.0));
+    }
+
+    @Test
+    public void testEquality() {
+        Constraint c1 = new TierConstraint(true, TierConstraint.CostType.ORDER, 3, 2, 1);
+        Constraint c2 = new TierConstraint(true, TierConstraint.CostType.ORDER, 3, 2, 1);
+
+        Constraint c3 = new TierConstraint(false, TierConstraint.CostType.TIER, 1);
+        Constraint c4 = new TierConstraint(false, TierConstraint.CostType.TIER, 1);
+
+        new EqualsTester()
+                .addEqualityGroup(c1, c2)
+                .addEqualityGroup(c3, c4)
+                .testEquals();
+    }
+}