shared: Adds method to remove elements from a slice.

Also adds tests for method.

Signed-off-by: Mark Laing <[email protected]>

shared/util.go

@@ -614,6 +614,28 @@ func StringInSlice(key string, list []string) bool {
 	return false
 }
 
+// RemoveElementsFromStringSlice returns a slice equivalent to removing the given elements from the given list.
+// Elements not present in the list are ignored.
+func RemoveElementsFromStringSlice(list []string, elements ...string) []string {
+	for i := len(elements) - 1; i >= 0; i-- {
+		element := elements[i]
+		match := false
+		for j := len(list) - 1; j >= 0; j-- {
+			if element == list[j] {
+				match = true
+				list = append(list[:j], list[j+1:]...)
+				break
+			}
+		}
+
+		if match {
+			elements = append(elements[:i], elements[i+1:]...)
+		}
+	}
+
+	return list
+}
+
 // StringHasPrefix returns true if value has one of the supplied prefixes.
 func StringHasPrefix(value string, prefixes ...string) bool {
 	for _, prefix := range prefixes {

shared/util_test.go

@@ -208,3 +208,43 @@ func TestHasKey(t *testing.T) {
 	assert.True(t, HasKey(1, m2))
 	assert.False(t, HasKey(0, m2))
 }
+
+func TestRemoveElementsFromStringSlice(t *testing.T) {
+	type test struct {
+		elementsToRemove []string
+		list             []string
+		expectedList     []string
+	}
+	tests := []test{
+		{
+			elementsToRemove: []string{"one", "two", "three"},
+			list:             []string{"one", "two", "three", "four", "five"},
+			expectedList:     []string{"four", "five"},
+		},
+		{
+			elementsToRemove: []string{"two", "three", "four"},
+			list:             []string{"one", "two", "three", "four", "five"},
+			expectedList:     []string{"one", "five"},
+		},
+		{
+			elementsToRemove: []string{"two", "three", "four"},
+			list:             []string{"two", "three"},
+			expectedList:     []string{},
+		},
+		{
+			elementsToRemove: []string{"two", "two", "two"},
+			list:             []string{"two"},
+			expectedList:     []string{},
+		},
+		{
+			elementsToRemove: []string{"two", "two", "two"},
+			list:             []string{"one", "two", "three", "four", "five"},
+			expectedList:     []string{"one", "three", "four", "five"},
+		},
+	}
+
+	for _, tt := range tests {
+		gotList := RemoveElementsFromStringSlice(tt.list, tt.elementsToRemove...)
+		assert.ElementsMatch(t, tt.expectedList, gotList)
+	}
+}