good good study, day day up!

vendor/gopl.io/ch11/word2/word_test.go

@@ -0,0 +1,148 @@
+// Copyright © 2016 Alan A. A. Donovan & Brian W. Kernighan.
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+
+package word
+
+import (
+	"fmt"
+	"math/rand"
+	"time"
+)
+
+//!+bench
+
+import "testing"
+
+//!-bench
+
+//!+test
+func TestIsPalindrome(t *testing.T) {
+	var tests = []struct {
+		input string
+		want  bool
+	}{
+		{"", true},
+		{"a", true},
+		{"aa", true},
+		{"ab", false},
+		{"kayak", true},
+		{"detartrated", true},
+		{"A man, a plan, a canal: Panama", true},
+		{"Evil I did dwell; lewd did I live.", true},
+		{"Able was I ere I saw Elba", true},
+		{"été", true},
+		{"Et se resservir, ivresse reste.", true},
+		{"palindrome", false}, // non-palindrome
+		{"desserts", false},   // semi-palindrome
+	}
+	for _, test := range tests {
+		if got := IsPalindrome(test.input); got != test.want {
+			t.Errorf("IsPalindrome(%q) = %v", test.input, got)
+		}
+	}
+}
+
+//!-test
+
+//!+bench
+func BenchmarkIsPalindrome(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		IsPalindrome("A man, a plan, a canal: Panama")
+	}
+}
+
+//!-bench
+
+//!+example
+
+func ExampleIsPalindrome() {
+	fmt.Println(IsPalindrome("A man, a plan, a canal: Panama"))
+	fmt.Println(IsPalindrome("palindrome"))
+	// Output:
+	// true
+	// false
+}
+
+//!-example
+
+/*
+//!+random
+import "math/rand"
+
+//!-random
+*/
+
+//!+random
+// randomPalindrome returns a palindrome whose length and contents
+// are derived from the pseudo-random number generator rng.
+func randomPalindrome(rng *rand.Rand) string {
+	n := rng.Intn(25) // random length up to 24
+	runes := make([]rune, n)
+	for i := 0; i < (n+1)/2; i++ {
+		r := rune(rng.Intn(0x1000)) // random rune up to '\u0999'
+		runes[i] = r
+		runes[n-1-i] = r
+	}
+	return string(runes)
+}
+
+func TestRandomPalindromes(t *testing.T) {
+	// Initialize a pseudo-random number generator.
+	seed := time.Now().UTC().UnixNano()
+	t.Logf("Random seed: %d", seed)
+	rng := rand.New(rand.NewSource(seed))
+
+	for i := 0; i < 1000; i++ {
+		p := randomPalindrome(rng)
+		if !IsPalindrome(p) {
+			t.Errorf("IsPalindrome(%q) = false", p)
+		}
+	}
+}
+
+//!-random
+
+/*
+// Answer for Exercicse 11.1: Modify randomPalindrome to exercise
+// IsPalindrome's handling of punctuation and spaces.
+
+// WARNING: the conversion r -> upper -> lower doesn't preserve
+// the value of r in some cases, e.g., µ Μ, ſ S, ı I
+
+// randomPalindrome returns a palindrome whose length and contents
+// are derived from the pseudo-random number generator rng.
+func randomNoisyPalindrome(rng *rand.Rand) string {
+	n := rng.Intn(25) // random length up to 24
+	runes := make([]rune, n)
+	for i := 0; i < (n+1)/2; i++ {
+		r := rune(rng.Intn(0x200)) // random rune up to \u99
+		runes[i] = r
+		r1 := r
+		if unicode.IsLetter(r) && unicode.IsLower(r) {
+			r = unicode.ToUpper(r)
+			if unicode.ToLower(r) != r1 {
+				fmt.Printf("cap? %c %c\n", r1, r)
+			}
+		}
+		runes[n-1-i] = r
+	}
+	return "?" + string(runes) + "!"
+}
+
+func TestRandomNoisyPalindromes(t *testing.T) {
+	// Initialize a pseudo-random number generator.
+	seed := time.Now().UTC().UnixNano()
+	t.Logf("Random seed: %d", seed)
+	rng := rand.New(rand.NewSource(seed))
+
+	n := 0
+	for i := 0; i < 1000; i++ {
+		p := randomNoisyPalindrome(rng)
+		if !IsPalindrome(p) {
+			t.Errorf("IsNoisyPalindrome(%q) = false", p)
+			n++
+		}
+	}
+	fmt.Fprintf(os.Stderr, "fail = %d\n", n)
+}
+*/