extract map merging to MapUtils (#156)

* Update MapUtils.groovy

* Update ConfigurationMerger.groovy

* tests

* forward skipNull

* Fix indent in tests

* More tests.

* MapUtils simplified wrt deep merge and pruneNulls

* Add test for isMap with null value

src/com/sap/piper/ConfigurationMerger.groovy

@@ -7,19 +7,9 @@ class ConfigurationMerger {
     @NonCPS
     static Map merge(Map configs, Set configKeys, Map defaults) {
         Map filteredConfig = configKeys?configs.subMap(configKeys):configs
-        Map merged = [:]
 
-        defaults = defaults ?: [:]
-
-        merged.putAll(defaults)
-
-        for(String key : filteredConfig.keySet())
-            if(MapUtils.isMap(filteredConfig[key]))
-                merged[key] = merge(filteredConfig[key], null, defaults[key])
-            else if(filteredConfig[key] != null)
-                merged[key] = filteredConfig[key]
-            // else: keep defaults value and omit null values from config
-        return merged
+        return MapUtils.merge(MapUtils.pruneNulls(defaults),
+                              MapUtils.pruneNulls(filteredConfig))
     }
 
     @NonCPS

src/com/sap/piper/MapUtils.groovy

@@ -7,4 +7,35 @@ class MapUtils implements Serializable {
     static boolean isMap(object){
         return object in Map
     }
+
+    @NonCPS
+    static Map pruneNulls(Map m) {
+
+        Map result = [:]
+
+        m = m ?: [:]
+
+        for(def e : m.entrySet())
+            if(isMap(e.value))
+                result[e.key] = pruneNulls(e.value)
+            else if(e.value != null)
+                result[e.key] = e.value
+        return result
+    }
+
+
+    @NonCPS
+    static Map merge(Map base, Map overlay) {
+
+        Map result = [:]
+
+        base = base ?: [:]
+
+        result.putAll(base)
+
+        for(def e : overlay.entrySet())
+            result[e.key] = isMap(e.value) ? merge(base[e.key], e.value) : e.value
+
+        return result
+    }
 }

test/groovy/com/sap/piper/MapUtilsTest.groovy

@@ -9,5 +9,38 @@ class MapUtilsTest {
     void testIsMap(){
         Assert.assertTrue('Map is not recognized as Map', MapUtils.isMap([:]))
         Assert.assertTrue('String is recognized as Map', !MapUtils.isMap('I am not a Map'))
+        Assert.assertFalse('Null value is recognized as Map', MapUtils.isMap(null))
+    }
+
+    @Test
+    void testMergeMapStraigtForward(){
+
+        Map a = [a: '1',
+                 c: [d: '1',
+                     e: '2']],
+             b = [b: '2',
+                  c: [d: 'x']];
+
+        Map merged = MapUtils.merge(a, b)
+
+        assert merged == [a: '1',
+                          b: '2',
+                          c: [d: 'x', e: '2']]
+    }
+
+    @Test
+    void testPruneNulls() {
+
+        Map m = [a: '1',
+                 b: 2,
+                 c: [ d: 'abc',
+                      e: '',
+                      n2: null],
+                 n1: null]
+
+        assert MapUtils.pruneNulls(m) == [ a: '1',
+                                           b: 2,
+                                           c: [ d: 'abc',
+                                                e: '']]
     }
 }