From 4ecbe749e45b4335e7426a493ab21c1fbe9e79cf Mon Sep 17 00:00:00 2001
From: Nathan Lowe <public@nlowe.me>
Date: Tue, 9 Jul 2019 23:23:35 -0400
Subject: [PATCH] Retention: Implement Filter: Keep Latest K

Signed-off-by: Nathan Lowe <public@nlowe.me>
---
 .../policy/rule/latestk/evaluator.go          | 10 +++-
 .../policy/rule/latestk/evaluator_test.go     | 57 +++++++++++++++++++
 2 files changed, 64 insertions(+), 3 deletions(-)
 create mode 100644 src/pkg/retention/policy/rule/latestk/evaluator_test.go

diff --git a/src/pkg/retention/policy/rule/latestk/evaluator.go b/src/pkg/retention/policy/rule/latestk/evaluator.go
index a49c5e1cc..cd4f137cd 100644
--- a/src/pkg/retention/policy/rule/latestk/evaluator.go
+++ b/src/pkg/retention/policy/rule/latestk/evaluator.go
@@ -38,8 +38,12 @@ type evaluator struct {
 
 // Process the candidates based on the rule definition
 func (e *evaluator) Process(artifacts []*res.Candidate) ([]*res.Candidate, error) {
-	// TODO: REPLACE SAMPLE CODE WITH REAL IMPLEMENTATION
-	return artifacts, nil
+	i := e.k
+	if i > len(artifacts) {
+		i = len(artifacts)
+	}
+
+	return artifacts[:i], nil
 }
 
 // Specify what action is performed to the candidates processed by this evaluator
@@ -51,7 +55,7 @@ func (e *evaluator) Action() string {
 func New(params rule.Parameters) rule.Evaluator {
 	if params != nil {
 		if param, ok := params[ParameterK]; ok {
-			if v, ok := param.(int); ok {
+			if v, ok := param.(int); ok && v >= 0 {
 				return &evaluator{
 					k: v,
 				}
diff --git a/src/pkg/retention/policy/rule/latestk/evaluator_test.go b/src/pkg/retention/policy/rule/latestk/evaluator_test.go
new file mode 100644
index 000000000..e88a2f49c
--- /dev/null
+++ b/src/pkg/retention/policy/rule/latestk/evaluator_test.go
@@ -0,0 +1,57 @@
+package latestk
+
+import (
+	"strconv"
+	"testing"
+
+	"github.com/goharbor/harbor/src/pkg/retention/policy/rule"
+	"github.com/goharbor/harbor/src/pkg/retention/res"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEvaluator_New(t *testing.T) {
+	tests := []struct {
+		Name      string
+		args      rule.Parameters
+		expectedK int
+	}{
+		{Name: "Valid", args: map[string]rule.Parameter{ParameterK: 5}, expectedK: 5},
+		{Name: "Default If Negative", args: map[string]rule.Parameter{ParameterK: -1}, expectedK: DefaultK},
+		{Name: "Default If Not Set", args: map[string]rule.Parameter{}, expectedK: DefaultK},
+		{Name: "Default If Wrong Type", args: map[string]rule.Parameter{ParameterK: "foo"}, expectedK: DefaultK},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Name, func(t *testing.T) {
+			e := New(tt.args).(*evaluator)
+
+			require.Equal(t, tt.expectedK, e.k)
+		})
+	}
+}
+
+func TestEvaluator_Process(t *testing.T) {
+	data := []*res.Candidate{{}, {}, {}, {}, {}}
+
+	tests := []struct {
+		k        int
+		expected int
+	}{
+		{k: 0, expected: 0},
+		{k: 1, expected: 1},
+		{k: 3, expected: 3},
+		{k: 5, expected: 5},
+		{k: 6, expected: 5},
+	}
+
+	for _, tt := range tests {
+		t.Run(strconv.Itoa(tt.k), func(t *testing.T) {
+			e := New(map[string]rule.Parameter{ParameterK: tt.k})
+
+			result, err := e.Process(data)
+
+			require.NoError(t, err)
+			require.Len(t, result, tt.expected)
+		})
+	}
+}