Add spec coverage for AggregateTimestampProvider

grails-datamapping-core/src/main/groovy/org/grails/datastore/gorm/timestamp/AggregateTimestampProvider.java

@@ -49,7 +49,7 @@ public <T> T createTimestamp(Class<T> dateTimeClass) {
                 }
             }
         } else {
-            return createTimestamp(timestampProviders.iterator().next(), dateTimeClass);
+            return createTimestamp(timestampProviders.getFirst(), dateTimeClass);
         }
         throw new IllegalArgumentException("dateTimeClass given as parameter isn't supported by any TimestampProvider. You should call supportsCreating first.");
     }

grails-datamapping-core/src/main/groovy/org/grails/datastore/gorm/timestamp/DefaultTimestampProvider.java

@@ -26,9 +26,7 @@
 
 /**
  * Default implementation of TimestampProvider
- *
  * supports creating timestamps for any class that supports a constructor that accepts a Long or long value.
- *
  * "currentTimeMillis" can be overrided in subclasses (useful for testing purposes)
  *
  */

grails-datamapping-core/src/test/groovy/org/grails/datastore/gorm/timestamp/AggregateTimestampProviderSpec.groovy

@@ -0,0 +1,126 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you 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
+ *
+ *    https://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.grails.datastore.gorm.timestamp
+
+import spock.lang.Specification
+
+class AggregateTimestampProviderSpec extends Specification {
+
+    AggregateTimestampProvider aggregateTimestampProvider = new AggregateTimestampProvider()
+
+    void "getTimestampProviders defaults to an empty list"() {
+        expect:
+        aggregateTimestampProvider.timestampProviders == []
+    }
+
+    void "setTimestampProviders stores the given providers"() {
+        given:
+        TimestampProvider dateProvider = Stub(TimestampProvider)
+        TimestampProvider stringProvider = Stub(TimestampProvider)
+
+        when:
+        aggregateTimestampProvider.timestampProviders = [dateProvider, stringProvider]
+
+        then:
+        aggregateTimestampProvider.timestampProviders == [dateProvider, stringProvider]
+    }
+
+    void "supportsCreating returns true when any delegate provider supports the class"() {
+        given:
+        TimestampProvider dateProvider = Stub(TimestampProvider) {
+            supportsCreating(Date) >> false
+        }
+        TimestampProvider stringProvider = Stub(TimestampProvider) {
+            supportsCreating(Date) >> true
+        }
+        aggregateTimestampProvider.timestampProviders = [dateProvider, stringProvider]
+
+        expect:
+        aggregateTimestampProvider.supportsCreating(Date)
+    }
+
+    void "supportsCreating returns false when no delegate provider supports the class"() {
+        given:
+        TimestampProvider dateProvider = Stub(TimestampProvider) {
+            supportsCreating(_) >> false
+        }
+        aggregateTimestampProvider.timestampProviders = [dateProvider]
+
+        expect:
+        !aggregateTimestampProvider.supportsCreating(Date)
+    }
+
+    void "supportsCreating returns false when there are no delegate providers"() {
+        expect:
+        !aggregateTimestampProvider.supportsCreating(Date)
+    }
+
+    void "createTimestamp delegates directly to the single registered provider"() {
+        given:
+        Date timestamp = new Date()
+        TimestampProvider onlyProvider = Stub(TimestampProvider) {
+            createTimestamp(Date) >> timestamp
+        }
+        aggregateTimestampProvider.timestampProviders = [onlyProvider]
+
+        expect:
+        aggregateTimestampProvider.createTimestamp(Date) == timestamp
+    }
+
+    void "createTimestamp with multiple providers delegates to the first provider that supports the class"() {
+        given:
+        Date timestamp = new Date()
+        TimestampProvider unsupportingProvider = Stub(TimestampProvider) {
+            supportsCreating(Date) >> false
+        }
+        TimestampProvider supportingProvider = Stub(TimestampProvider) {
+            supportsCreating(Date) >> true
+            createTimestamp(Date) >> timestamp
+        }
+        aggregateTimestampProvider.timestampProviders = [unsupportingProvider, supportingProvider]
+
+        expect:
+        aggregateTimestampProvider.createTimestamp(Date) == timestamp
+    }
+
+    void "createTimestamp with multiple providers throws when none support the class"() {
+        given:
+        TimestampProvider firstProvider = Stub(TimestampProvider) {
+            supportsCreating(Date) >> false
+        }
+        TimestampProvider secondProvider = Stub(TimestampProvider) {
+            supportsCreating(Date) >> false
+        }
+        aggregateTimestampProvider.timestampProviders = [firstProvider, secondProvider]
+
+        when:
+        aggregateTimestampProvider.createTimestamp(Date)
+
+        then:
+        thrown(IllegalArgumentException)
+    }
+
+    void "createTimestamp with no registered providers throws"() {
+        when:
+        aggregateTimestampProvider.createTimestamp(Date)
+
+        then:
+        thrown(NoSuchElementException)
+    }
+}