forked from sneak/util
clawbot
daaea4e10f
TruncateString returns at most the requested number of characters from the start of a string, counting characters rather than bytes so a multi-byte character is never cut in half. Comes with a doc comment and table-driven tests. (closes #5) Model: opus-5
42 lines
1.1 KiB
Go
42 lines
1.1 KiB
Go
package util
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import "testing"
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func TestTruncateString(t *testing.T) {
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tests := []struct {
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name string
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input string
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max int
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expected string
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}{
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{"shorter than the limit", "abc", 5, "abc"},
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{"exactly at the limit", "abc", 3, "abc"},
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{"longer than the limit", "abcdef", 3, "abc"},
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{"max of one", "abc", 1, "a"},
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{"max of zero", "abc", 0, ""},
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{"negative max", "abc", -1, ""},
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{"empty string", "", 3, ""},
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{"multi-byte characters kept whole", "héllo", 3, "hél"},
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{"multi-byte characters below the limit", "héllo", 99, "héllo"},
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{"characters outside the basic plane", "a😀b", 2, "a😀"},
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}
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for _, test := range tests {
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t.Run(test.name, func(t *testing.T) {
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got := TruncateString(test.input, test.max)
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if got != test.expected {
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t.Errorf("expected %q got %q", test.expected, got)
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}
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})
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}
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}
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func TestTruncateStringCountsCharactersNotBytes(t *testing.T) {
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// Each of these characters is two bytes long, so a byte-based cut at
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// three would leave half a character behind.
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got := TruncateString("äöü", 3)
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if got != "äöü" {
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t.Errorf("expected %q got %q", "äöü", got)
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}
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}
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