fix (utils) : [CRW-8603] Use slice of string instead of apimachinery Set to merge events

We were previously using apimachinery Set that is internally based on Map, an unordered data structure.
Due to this we were losing the original insertion order defined in the devfile while merging it, List()
call returns the elements in non-deterministic order, as it internally ranges over the map.

Use string slice to preserve insertion order of all event types.

Signed-off-by: Rohan Kumar <[email protected]>

Author: rohanKanojia

pkg/utils/overriding/merging.go

@@ -108,19 +108,19 @@ func MergeDevWorkspaceTemplateSpec(
 		}
 	}
 
-	preStartCommands := sets.String{}
-	postStartCommands := sets.String{}
-	preStopCommands := sets.String{}
-	postStopCommands := sets.String{}
+	var preStartCommands []string
+	var postStartCommands []string
+	var preStopCommands []string
+	var postStopCommands []string
 	for _, content := range allContents {
 		if content.Events != nil {
 			if result.Events == nil {
 				result.Events = &dw.Events{}
 			}
-			preStartCommands = preStartCommands.Union(sets.NewString(content.Events.PreStart...))
-			postStartCommands = postStartCommands.Union(sets.NewString(content.Events.PostStart...))
-			preStopCommands = preStopCommands.Union(sets.NewString(content.Events.PreStop...))
-			postStopCommands = postStopCommands.Union(sets.NewString(content.Events.PostStop...))
+			preStartCommands = UnionStrings(preStartCommands, content.Events.PreStart)
+			postStartCommands = UnionStrings(postStartCommands, content.Events.PostStart)
+			preStopCommands = UnionStrings(preStopCommands, content.Events.PreStop)
+			postStopCommands = UnionStrings(postStopCommands, content.Events.PostStop)
 		}
 
 		if len(content.Variables) > 0 {
@@ -147,10 +147,10 @@ func MergeDevWorkspaceTemplateSpec(
 	}
 
 	if result.Events != nil {
-		result.Events.PreStart = preStartCommands.List()
-		result.Events.PostStart = postStartCommands.List()
-		result.Events.PreStop = preStopCommands.List()
-		result.Events.PostStop = postStopCommands.List()
+		result.Events.PreStart = preStartCommands
+		result.Events.PostStart = postStartCommands
+		result.Events.PreStop = preStopCommands
+		result.Events.PostStop = postStopCommands
 	}
 
 	return &result, nil

pkg/utils/overriding/merging_test.go

@@ -134,3 +134,24 @@ func TestMergingOnlyParent(t *testing.T) {
 		assert.Equal(t, &expectedDWT, gotDWT)
 	}
 }
+
+func TestMergePostStartInOrder(t *testing.T) {
+	// Given
+	baseFile := "test-fixtures/merges/multiple-post-start/main.yaml"
+	parentFile := "test-fixtures/merges/multiple-post-start/plugin.yaml"
+	resultFile := "test-fixtures/merges/multiple-post-start/result.yaml"
+
+	baseDWT := dw.DevWorkspaceTemplateSpecContent{}
+	parentDWT := dw.DevWorkspaceTemplateSpecContent{}
+	expectedDWT := dw.DevWorkspaceTemplateSpecContent{}
+
+	readFileToStruct(t, baseFile, &baseDWT)
+	readFileToStruct(t, parentFile, &parentDWT)
+	readFileToStruct(t, resultFile, &expectedDWT)
+
+	// When + Then
+	gotDWT, err := MergeDevWorkspaceTemplateSpec(&baseDWT, &parentDWT)
+	if assert.NoError(t, err) {
+		assert.Equal(t, &expectedDWT, gotDWT)
+	}
+}

pkg/utils/overriding/test-fixtures/merges/events-merge/result.yaml

@@ -1,26 +1,26 @@
 events:
   preStart:
-    - "preStartFromMainContent"
     - "preStartFromParent"
     - "preStartFromPlugin"
+    - "preStartFromMainContent"
   preStop:
-    - "preStopFromMainContent"
     - "preStopFromParent"
     - "preStopFromPlugin"
+    - "preStopFromMainContent"
   postStart:
-    - "postStartFromMainContent"
     - "postStartFromParent"
     - "postStartFromPlugin"
+    - "postStartFromMainContent"
   postStop:
-    - "postStopFromMainContent"
     - "postStopFromParent"
     - "postStopFromPlugin"
+    - "postStopFromMainContent"
 
 # Note:
 #
 # The command Id are merged *per-event type*
 # from the commands of the corresponding event type
-# in parent, plugins and devfile main content. 
+# in parent, plugins and devfile main content.
 #
 # The command Ids in each event type are unordered sets.
 # Only event types are ordered; no guarantee is provided that
@@ -29,4 +29,4 @@ events:
 #
 # However in the test results, as it will happen usually,
 # command ids of a given event type will simply be ordered
-# in alphabetical order. 
+# in alphabetical order.

pkg/utils/overriding/test-fixtures/merges/multiple-post-start/main.yaml

@@ -0,0 +1,9 @@
+parent:
+  uri: "anyParent"
+components:
+  - plugin:
+      uri: "aCustomLocation"
+    name: "the-only-plugin"
+events:
+  postStart:
+    - "init-che-code-command"

pkg/utils/overriding/test-fixtures/merges/multiple-post-start/plugin.yaml

@@ -0,0 +1,5 @@
+events:
+  postStart:
+    - "event-one"
+    - "event-two"
+    - "event-three"

pkg/utils/overriding/test-fixtures/merges/multiple-post-start/result.yaml

@@ -0,0 +1,9 @@
+events:
+  preStart: []
+  preStop: []
+  postStop: []
+  postStart:
+    - "event-one"
+    - "event-two"
+    - "event-three"
+    - "init-che-code-command"

pkg/utils/overriding/utils.go

@@ -32,3 +32,34 @@ func handleUnmarshal(j []byte) (map[string]interface{}, error) {
 	}
 	return m, nil
 }
+
+// UnionStrings returns the union of two string slices, preserving the order
+// of first occurrence and removing duplicates.
+//
+// Elements from the first slice `a` are added in order. Elements from the second
+// slice `b` are appended only if they do not already exist in `a`.
+//
+// The returned slice is guaranteed to be non-nil, even if both input slices are nil.
+//
+// Example:
+//
+//	UnionStrings([]string{"a", "b"}, []string{"b", "c"})
+//	// Returns: []string{"a", "b", "c"}
+func UnionStrings(a, b []string) []string {
+	alreadyExistsInList := make(map[string]bool)
+	result := make([]string, 0)
+
+	for _, s := range a {
+		if !alreadyExistsInList[s] {
+			alreadyExistsInList[s] = true
+			result = append(result, s)
+		}
+	}
+	for _, s := range b {
+		if !alreadyExistsInList[s] {
+			alreadyExistsInList[s] = true
+			result = append(result, s)
+		}
+	}
+	return result
+}

pkg/utils/overriding/utils_test.go

@@ -0,0 +1,84 @@
+package overriding
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestUnionStrings(t *testing.T) {
+	tests := []struct {
+		name     string
+		a        []string
+		b        []string
+		expected []string
+	}{
+		{
+			name:     "both empty",
+			a:        []string{},
+			b:        []string{},
+			expected: []string{},
+		},
+		{
+			name:     "first is nil, second is empty",
+			a:        nil,
+			b:        []string{},
+			expected: []string{},
+		},
+		{
+			name:     "first is empty, second is nil",
+			a:        []string{},
+			b:        nil,
+			expected: []string{},
+		},
+		{
+			name:     "both are nil",
+			a:        nil,
+			b:        nil,
+			expected: []string{},
+		},
+		{
+			name:     "no overlap",
+			a:        []string{"x", "y"},
+			b:        []string{"a", "b"},
+			expected: []string{"x", "y", "a", "b"},
+		},
+		{
+			name:     "partial overlap",
+			a:        []string{"a", "b"},
+			b:        []string{"b", "c"},
+			expected: []string{"a", "b", "c"},
+		},
+		{
+			name:     "duplicate in same slice",
+			a:        []string{"a", "a", "b"},
+			b:        []string{"b", "c"},
+			expected: []string{"a", "b", "c"},
+		},
+		{
+			name:     "only duplicates",
+			a:        []string{"a", "b"},
+			b:        []string{"a", "b"},
+			expected: []string{"a", "b"},
+		},
+		{
+			name:     "preserves order",
+			a:        []string{"c", "a"},
+			b:        []string{"b", "a", "d"},
+			expected: []string{"c", "a", "b", "d"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			actual := UnionStrings(tt.a, tt.b)
+
+			if actual == nil {
+				t.Errorf("expected non-nil slice, got nil")
+			}
+
+			if !reflect.DeepEqual(actual, tt.expected) {
+				t.Errorf("UnionStrings(%v, %v) = %v; want %v", tt.a, tt.b, actual, tt.expected)
+			}
+		})
+	}
+}