test: add unit tests for part two

internal/2017/DayThree/code_test.go

@@ -39,3 +39,46 @@ func TestPartOne(t *testing.T) {
 		})
 	}
 }
+
+func TestPartTwo(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    int
+		expected int
+	}{
+		{
+			name:     "input 1 returns first value larger than 1",
+			input:    1,
+			expected: 2,
+		},
+		{
+			name:     "input 2 returns first value larger than 2",
+			input:    2,
+			expected: 4,
+		},
+		{
+			name:     "input 4 returns first value larger than 4",
+			input:    4,
+			expected: 5,
+		},
+		{
+			name:     "input 5 returns first value larger than 5",
+			input:    5,
+			expected: 10,
+		},
+		{
+			name:     "input 747 returns first value larger than 747",
+			input:    747,
+			expected: 806,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := PartTwo(tt.input)
+			if got != tt.expected {
+				t.Errorf("PartTwo() = %d, want %d", got, tt.expected)
+			}
+		})
+	}
+}