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70 lines
1.8 KiB
Go
70 lines
1.8 KiB
Go
// Unit testing is an important part of writing
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// principled Go programs. The `testing` package
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// provides the tools we need to write unit tests
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// and the `go test` command runs tests.
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// For the sake of demonstration, this code is in package
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// `main`, but it could be any package. Testing code
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// typically lives in the same package as the code it tests.
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package main
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import (
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"fmt"
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"testing"
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)
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// We'll be testing this simple implementation of an
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// integer minimum. Typically, the code we're testing
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// would be in a source file named something like
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// `intutils.go`, and the test file for it would then
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// be named `intutils_test.go`.
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func IntMin(a, b int) int {
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if a < b {
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return a
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} else {
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return b
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}
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}
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// A test is created by writing a function with a name
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// beginning with `Test`.
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func TestIntMinBasic(t *testing.T) {
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ans := IntMin(2, -2)
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if ans != -2 {
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// `t.Error*` will report test failures but continue
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// executing the test. `t.Fail*` will report test
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// failures and stop the test immediately.
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t.Errorf("IntMin(2, -2) = %d; want -2", ans)
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}
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}
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// Writing tests can be repetitive, so it's idiomatic to
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// use a *table-driven style*, where test inputs and
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// expected outputs are listed in a table and a single loop
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// walks over them and performs the test logic.
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func TestIntMinTableDriven(t *testing.T) {
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var tests = []struct {
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a, b int
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want int
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}{
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{0, 1, 0},
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{1, 0, 0},
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{2, -2, -2},
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{0, -1, -1},
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{-1, 0, -1},
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}
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for _, tt := range tests {
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// t.Run enables running "subtests", one for each
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// table entry. These are shown separately
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// when executing `go test -v`.
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testname := fmt.Sprintf("%d,%d", tt.a, tt.b)
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t.Run(testname, func(t *testing.T) {
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ans := IntMin(tt.a, tt.b)
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if ans != tt.want {
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t.Errorf("got %d, want %d", ans, tt.want)
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}
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})
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}
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}
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