dict/merge: Add ability to merge multiple dicts, update test and docs

dict.go

@@ -75,10 +75,12 @@ func dict(v ...interface{}) map[string]interface{} {
 	return dict
 }
 
-func merge(dst map[string]interface{}, src map[string]interface{}) interface{} {
-	if err := mergo.Merge(&dst, src); err != nil {
-		// Swallow errors inside of a template.
-		return ""
+func merge(dst map[string]interface{}, srcs ...map[string]interface{}) interface{} {
+	for _, src := range srcs {
+		if err := mergo.Merge(&dst, src); err != nil {
+			// Swallow errors inside of a template.
+			return ""
+		}
 	}
 	return dst
 }

dict_test.go

@@ -138,13 +138,20 @@ func TestCompact(t *testing.T) {
 
 func TestMerge(t *testing.T) {
 	dict := map[string]interface{}{
-		"src": map[string]interface{}{
+		"src2": map[string]interface{}{
+			"h": 10,
+			"i": "i",
+			"j": "j",
+		},
+		"src1": map[string]interface{}{
 			"a": 1,
 			"b": 2,
 			"d": map[string]interface{}{
 				"e": "four",
 			},
 			"g": []int{6, 7},
+			"i": "aye",
+			"j": "jay",
 		},
 		"dst": map[string]interface{}{
 			"a": "one",
@@ -153,22 +160,26 @@ func TestMerge(t *testing.T) {
 				"f": 5,
 			},
 			"g": []int{8, 9},
+			"i": "eye",
 		},
 	}
-	tpl := `{{merge .dst .src}}`
+	tpl := `{{merge .dst .src1 .src2}}`
 	_, err := runRaw(tpl, dict)
 	if err != nil {
 		t.Error(err)
 	}
 	expected := map[string]interface{}{
 		"a": "one", // key overridden
-		"b": 2,     // merged from src
+		"b": 2,     // merged from src1
 		"c": 3,     // merged from dst
 		"d": map[string]interface{}{ // deep merge
 			"e": "four",
 			"f": 5,
 		},
 		"g": []int{8, 9}, // overridden - arrays are not merged
+		"h": 10,          // merged from src2
+		"i": "eye",       // overridden twice
+		"j": "jay",       // overridden and merged
 	}
 	assert.Equal(t, expected, dict["dst"])
 }

docs/dicts.md

@@ -77,10 +77,10 @@ matching key out of a collection of dictionaries.
 
 ## merge
 
-Merge two dictionaries into one, giving precedence to the dest dictionary:
+Merge two or more dictionaries into one, giving precedence to the dest dictionary:
 
 ```
-$newdict := merge $dest $source
+$newdict := merge $dest $source1 $source2
 ```
 
 This is a deep merge operation.