func genTablesTest()

in cases/gen.go [630:760]
112 lines of code
24 McCabe index (conditional complexity)

func genTablesTest() {
	w := &bytes.Buffer{}

	fmt.Fprintln(w, "var (")
	printProperties(w, "DerivedCoreProperties.txt", "Case_Ignorable", verifyIgnore)

	// We discard the output as we know we have perfect functions. We run them
	// just to verify the properties are correct.
	n := printProperties(ioutil.Discard, "DerivedCoreProperties.txt", "Cased", verifyCased)
	n += printProperties(ioutil.Discard, "DerivedCoreProperties.txt", "Lowercase", verifyLower)
	n += printProperties(ioutil.Discard, "DerivedCoreProperties.txt", "Uppercase", verifyUpper)
	if n > 0 {
		log.Fatalf("One of the discarded properties does not have a perfect filter.")
	}

	// <code>; <lower> ; <title> ; <upper> ; (<condition_list> ;)?
	fmt.Fprintln(w, "\tspecial = map[rune]struct{ toLower, toTitle, toUpper string }{")
	parse("SpecialCasing.txt", func(p *ucd.Parser) {
		// Skip conditional entries.
		if p.String(4) != "" {
			return
		}
		r := p.Rune(0)
		fmt.Fprintf(w, "\t\t0x%04x: {%q, %q, %q},\n",
			r, string(p.Runes(1)), string(p.Runes(2)), string(p.Runes(3)))
	})
	fmt.Fprint(w, "\t}\n\n")

	// <code>; <type>; <runes>
	table := map[rune]struct{ simple, full, special string }{}
	parse("CaseFolding.txt", func(p *ucd.Parser) {
		r := p.Rune(0)
		t := p.String(1)
		v := string(p.Runes(2))
		if t != "T" && v == string(unicode.ToLower(r)) {
			return
		}
		x := table[r]
		switch t {
		case "C":
			x.full = v
			x.simple = v
		case "S":
			x.simple = v
		case "F":
			x.full = v
		case "T":
			x.special = v
		}
		table[r] = x
	})
	fmt.Fprintln(w, "\tfoldMap = map[rune]struct{ simple, full, special string }{")
	for r := rune(0); r < 0x10FFFF; r++ {
		x, ok := table[r]
		if !ok {
			continue
		}
		fmt.Fprintf(w, "\t\t0x%04x: {%q, %q, %q},\n", r, x.simple, x.full, x.special)
	}
	fmt.Fprint(w, "\t}\n\n")

	// Break property
	notBreak := map[rune]bool{}
	parse("auxiliary/WordBreakProperty.txt", func(p *ucd.Parser) {
		switch p.String(1) {
		case "Extend", "Format", "MidLetter", "MidNumLet", "Single_Quote",
			"ALetter", "Hebrew_Letter", "Numeric", "ExtendNumLet", "ZWJ":
			notBreak[p.Rune(0)] = true
		}
	})

	fmt.Fprintln(w, "\tbreakProp = []struct{ lo, hi rune }{")
	inBreak := false
	for r := rune(0); r <= lastRuneForTesting; r++ {
		if isBreak := !notBreak[r]; isBreak != inBreak {
			if isBreak {
				fmt.Fprintf(w, "\t\t{0x%x, ", r)
			} else {
				fmt.Fprintf(w, "0x%x},\n", r-1)
			}
			inBreak = isBreak
		}
	}
	if inBreak {
		fmt.Fprintf(w, "0x%x},\n", lastRuneForTesting)
	}
	fmt.Fprint(w, "\t}\n\n")

	// Word break test
	// Filter out all samples that do not contain cased characters.
	cased := map[rune]bool{}
	parse("DerivedCoreProperties.txt", func(p *ucd.Parser) {
		if p.String(1) == "Cased" {
			cased[p.Rune(0)] = true
		}
	})

	fmt.Fprintln(w, "\tbreakTest = []string{")
	parse("auxiliary/WordBreakTest.txt", func(p *ucd.Parser) {
		c := strings.Split(p.String(0), " ")

		const sep = '|'
		numCased := 0
		test := ""
		for ; len(c) >= 2; c = c[2:] {
			if c[0] == "÷" && test != "" {
				test += string(sep)
			}
			i, err := strconv.ParseUint(c[1], 16, 32)
			r := rune(i)
			if err != nil {
				log.Fatalf("Invalid rune %q.", c[1])
			}
			if r == sep {
				log.Fatalf("Separator %q not allowed in test data. Pick another one.", sep)
			}
			if cased[r] {
				numCased++
			}
			test += string(r)
		}
		if numCased > 1 {
			fmt.Fprintf(w, "\t\t%q,\n", test)
		}
	})
	fmt.Fprintln(w, "\t}")

	fmt.Fprintln(w, ")")

	gen.WriteVersionedGoFile("tables_test.go", "cases", w.Bytes())
}