feat: unit tests

Signed-off-by: skidoodle <contact@albert.lol>

internal/app/retention_test.go

@@ -0,0 +1,52 @@
+package app
+
+import (
+	"testing"
+	"time"
+)
+
+func TestCalculateRetention(t *testing.T) {
+	maxMB := int64(100)
+
+	tests := []struct {
+		name     string
+		fileSize int64
+		wantMin  time.Duration
+		wantMax  time.Duration
+	}{
+		{
+			name:     "Tiny file (Max retention)",
+			fileSize: 1024,
+			wantMin:  MaxRetention - time.Hour,
+			wantMax:  MaxRetention,
+		},
+		{
+			name:     "Max size file (Min retention)",
+			fileSize: 100 * MegaByte,
+			wantMin:  MinRetention,
+			wantMax:  MinRetention + time.Minute,
+		},
+		{
+			name:     "Half size file (Somewhere in between)",
+			fileSize: 50 * MegaByte,
+			wantMin: 24 * time.Hour,
+			wantMax: MaxRetention,
+		},
+		{
+			name:     "Oversized file (Min retention)",
+			fileSize: 200 * MegaByte,
+			wantMin:  MinRetention,
+			wantMax:  MinRetention + time.Minute,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got := CalculateRetention(tc.fileSize, maxMB)
+			if got < tc.wantMin || got > tc.wantMax {
+				t.Errorf("Retention for size %d: got %v, want between %v and %v",
+					tc.fileSize, got, tc.wantMin, tc.wantMax)
+			}
+		})
+	}
+}