Povide coverage for LinkSetViewAggregations

Author: sven1103

src/test/groovy/life/qbic/compass/LinkSetViewAggregationsSpec.groovy

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+package life.qbic.compass
+
+import life.qbic.compass.SignPostingProcessor.LinkSetViewAggregationMode
+import life.qbic.compass.processing.FailOnMultipleLinkSetViewAggregation
+import life.qbic.compass.processing.MergeLinkSetViewAggregation
+import life.qbic.compass.processing.NoLinkSetViewAggregation
+import life.qbic.compass.processing.TakeFirstLinkSetViewAggregation
+import spock.lang.Specification
+import spock.lang.Unroll
+
+class LinkSetViewAggregationsSpec extends Specification {
+
+    @Unroll
+    def "routes mode #mode to strategy type #expectedType.simpleName"() {
+        when:
+        def strategy = LinkSetViewAggregations.forMode(mode)
+
+        then:
+        strategy != null
+        strategy.class == expectedType
+
+        where:
+        mode                                        || expectedType
+        LinkSetViewAggregationMode.NONE             || NoLinkSetViewAggregation
+        LinkSetViewAggregationMode.FIRST            || TakeFirstLinkSetViewAggregation
+        LinkSetViewAggregationMode.MERGE            || MergeLinkSetViewAggregation
+        LinkSetViewAggregationMode.FAIL_ON_MULTIPLE || FailOnMultipleLinkSetViewAggregation
+    }
+
+    @Unroll
+    def "returns singleton instance for mode #mode (same object on repeated calls)"() {
+        when:
+        def s1 = LinkSetViewAggregations.forMode(mode as LinkSetViewAggregationMode)
+        def s2 = LinkSetViewAggregations.forMode(mode as LinkSetViewAggregationMode)
+        def s3 = LinkSetViewAggregations.forMode(mode as LinkSetViewAggregationMode)
+
+        then: "Groovy identity check"
+        s1.is(s2)
+        s2.is(s3)
+
+        where:
+        mode << LinkSetViewAggregationMode.values()
+    }
+
+    def "different modes return different instances (no accidental aliasing)"() {
+        when:
+        def strategies = LinkSetViewAggregationMode.values()
+                .collect { LinkSetViewAggregations.forMode(it) }
+
+        then: "all strategies are pairwise distinct by identity"
+        def identities = strategies.collect { System.identityHashCode(it) }
+        identities.size() == identities.toSet().size()
+
+        and: "sanity: exactly one instance per mode"
+        strategies.size() == LinkSetViewAggregationMode.values().length
+    }
+
+    def "null mode throws NullPointerException"() {
+        when:
+        LinkSetViewAggregations.forMode(null)
+
+        then:
+        thrown(NullPointerException)
+    }
+}