test(channelserver): add tests for guild member and gacha functions

Add comprehensive tests for pure logic functions:
- GuildMember.CanRecruit() and IsSubLeader() methods
- getRandomEntries() for gacha weighted/box selection

All targeted functions now have 100% coverage.

server/channelserver/handlers_guild_member_test.go

@@ -0,0 +1,209 @@
+package channelserver
+
+import (
+	"testing"
+)
+
+func TestGuildMember_CanRecruit(t *testing.T) {
+	tests := []struct {
+		name     string
+		member   GuildMember
+		expected bool
+	}{
+		{
+			name: "recruiter flag true",
+			member: GuildMember{
+				Recruiter:  true,
+				OrderIndex: 10,
+				IsLeader:   false,
+			},
+			expected: true,
+		},
+		{
+			name: "order index 1",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 1,
+				IsLeader:   false,
+			},
+			expected: true,
+		},
+		{
+			name: "order index 2",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 2,
+				IsLeader:   false,
+			},
+			expected: true,
+		},
+		{
+			name: "order index 3",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 3,
+				IsLeader:   false,
+			},
+			expected: true,
+		},
+		{
+			name: "order index 0 (sub-leader)",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 0,
+				IsLeader:   false,
+			},
+			expected: true,
+		},
+		{
+			name: "order index 4 cannot recruit",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 4,
+				IsLeader:   false,
+			},
+			expected: false,
+		},
+		{
+			name: "order index 5 cannot recruit",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 5,
+				IsLeader:   false,
+			},
+			expected: false,
+		},
+		{
+			name: "is leader can recruit",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 100,
+				IsLeader:   true,
+			},
+			expected: true,
+		},
+		{
+			name: "regular member cannot recruit",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 10,
+				IsLeader:   false,
+			},
+			expected: false,
+		},
+		{
+			name: "all flags true",
+			member: GuildMember{
+				Recruiter:  true,
+				OrderIndex: 1,
+				IsLeader:   true,
+			},
+			expected: true,
+		},
+		{
+			name: "high order index with leader",
+			member: GuildMember{
+				Recruiter:  false,
+				OrderIndex: 255,
+				IsLeader:   true,
+			},
+			expected: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := tt.member.CanRecruit()
+			if result != tt.expected {
+				t.Errorf("CanRecruit() = %v, expected %v (Recruiter=%v, OrderIndex=%d, IsLeader=%v)",
+					result, tt.expected, tt.member.Recruiter, tt.member.OrderIndex, tt.member.IsLeader)
+			}
+		})
+	}
+}
+
+func TestGuildMember_IsSubLeader(t *testing.T) {
+	tests := []struct {
+		name       string
+		orderIndex uint8
+		expected   bool
+	}{
+		{
+			name:       "order index 0",
+			orderIndex: 0,
+			expected:   true,
+		},
+		{
+			name:       "order index 1",
+			orderIndex: 1,
+			expected:   true,
+		},
+		{
+			name:       "order index 2",
+			orderIndex: 2,
+			expected:   true,
+		},
+		{
+			name:       "order index 3",
+			orderIndex: 3,
+			expected:   true,
+		},
+		{
+			name:       "order index 4",
+			orderIndex: 4,
+			expected:   false,
+		},
+		{
+			name:       "order index 5",
+			orderIndex: 5,
+			expected:   false,
+		},
+		{
+			name:       "order index 100",
+			orderIndex: 100,
+			expected:   false,
+		},
+		{
+			name:       "order index 255",
+			orderIndex: 255,
+			expected:   false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			member := GuildMember{OrderIndex: tt.orderIndex}
+			result := member.IsSubLeader()
+			if result != tt.expected {
+				t.Errorf("IsSubLeader() with OrderIndex=%d = %v, expected %v",
+					tt.orderIndex, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestGuildMember_CanRecruit_Priority(t *testing.T) {
+	// Test that Recruiter flag takes priority (short-circuit)
+	member := GuildMember{
+		Recruiter:  true,
+		OrderIndex: 100, // Would fail OrderIndex check
+		IsLeader:   false,
+	}
+
+	if !member.CanRecruit() {
+		t.Error("Recruiter flag should allow recruiting regardless of OrderIndex")
+	}
+}
+
+func TestGuildMember_CanRecruit_OrderIndexBoundary(t *testing.T) {
+	// Test the exact boundary at OrderIndex == 3 vs 4
+	member3 := GuildMember{Recruiter: false, OrderIndex: 3, IsLeader: false}
+	member4 := GuildMember{Recruiter: false, OrderIndex: 4, IsLeader: false}
+
+	if !member3.CanRecruit() {
+		t.Error("OrderIndex 3 should be able to recruit")
+	}
+	if member4.CanRecruit() {
+		t.Error("OrderIndex 4 should NOT be able to recruit")
+	}
+}