Initial version: Panic, Fatal, Exit, and Log.

Author: pat42smith

LICENSE

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+Copyright (c) 2023 Patrick Smith
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# Go tests
+
+[![Go Reference](https://pkg.go.dev/badge/github.com/pat42smith/or.svg)](https://pkg.go.dev/github.com/pat42smith/or)
+
+This repository provides some simple utilities for handling errors in Go code.

error_test.go

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+// Copyright 2023 Patrick Smith
+// Use of this source code is subject to the MIT-style license in the LICENSE file.
+
+package or
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/pat42smith/gotest"
+)
+
+// Check that non-nil errors are handled correctly.
+// Exit and Log need to be tested in a separate process,
+// so they are not included here.
+
+var disaster = errors.New("disaster")
+
+func jabber0() error {
+	return disaster
+}
+
+func jabber1() (string, error) {
+	return "'Twas", disaster
+}
+
+func jabber2() (string, string, error) {
+	return "brillig,", "and", disaster
+}
+
+func jabber3() (string, string, string, error) {
+	return "the", "slithy", "toves", disaster
+}
+
+func jabber4() (string, string, string, string, error) {
+	return "Did", "gyre", "and", "gimble", disaster
+}
+
+func jabber5() (string, string, string, string, string, error) {
+	return "in", "the", "wabe;", "All", "mimsy", disaster
+}
+
+func checkPanic(t *testing.T, f func()) {
+	t.Helper()
+	p := gotest.MustPanic(t, f)
+	gotest.Expect(t, disaster, p.(error))
+}
+
+func TestErrorPanic(t *testing.T) {
+	checkPanic(t, func() {
+		Panic0(jabber0())
+	})
+	checkPanic(t, func() {
+		Panic1(jabber1())
+	})
+	checkPanic(t, func() {
+		Panic2(jabber2())
+	})
+	checkPanic(t, func() {
+		Panic3(jabber3())
+	})
+	checkPanic(t, func() {
+		Panic4(jabber4())
+	})
+	checkPanic(t, func() {
+		Panic5(jabber5())
+	})
+}
+
+func checkFatal(t *testing.T, f func(*gotest.StubReporter)) {
+	t.Helper()
+	var sr gotest.StubReporter
+	// StubReporter.Fatal actually returns, so Fataln should panic.
+	gotest.MustPanic(t, func() {
+		f(&sr)
+	})
+	sr.Expect(t, true, true, "disaster\n")
+}
+
+func TestErrorFatal(t *testing.T) {
+	checkFatal(t, func(sr *gotest.StubReporter) {
+		Fatal0(jabber0())(sr)
+	})
+	checkFatal(t, func(sr *gotest.StubReporter) {
+		Fatal1(jabber1())(sr)
+	})
+	checkFatal(t, func(sr *gotest.StubReporter) {
+		Fatal2(jabber2())(sr)
+	})
+	checkFatal(t, func(sr *gotest.StubReporter) {
+		Fatal3(jabber3())(sr)
+	})
+	checkFatal(t, func(sr *gotest.StubReporter) {
+		Fatal4(jabber4())(sr)
+	})
+	checkFatal(t, func(sr *gotest.StubReporter) {
+		Fatal5(jabber5())(sr)
+	})
+}
+
+func checkHandle(t *testing.T, f func(Handler)) {
+	var saved error
+	p := gotest.MustPanic(t, func() {
+		f(func(e error) {
+			saved = e
+			panic(e)
+		})
+	})
+	gotest.Require(t, saved == disaster && p.(error) == disaster)
+
+	saved = nil
+	p = gotest.MustPanic(t, func() {
+		f(func(e error) {
+			saved = e
+		})
+	})
+	gotest.Require(t, saved == disaster && p.(string) == "Error handler returned")
+}
+
+func TestErrorHandle(t *testing.T) {
+	checkHandle(t, func(h Handler) {
+		Handle0(jabber0())(h)
+	})
+	checkHandle(t, func(h Handler) {
+		Handle1(jabber1())(h)
+	})
+	checkHandle(t, func(h Handler) {
+		Handle2(jabber2())(h)
+	})
+	checkHandle(t, func(h Handler) {
+		Handle3(jabber3())(h)
+	})
+	checkHandle(t, func(h Handler) {
+		Handle4(jabber4())(h)
+	})
+	checkHandle(t, func(h Handler) {
+		Handle5(jabber5())(h)
+	})
+}

exit.go

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+// Copyright 2023 Patrick Smith
+// Use of this source code is subject to the MIT-style license in the LICENSE file.
+
+package or
+
+import (
+	"fmt"
+	"os"
+)
+
+// Exit0, if e is not nil, prints e to standard error and then calls os.Exit(1).
+func Exit0(e error) {
+	if e != nil {
+		fmt.Fprintln(os.Stderr, e)
+		os.Exit(1)
+	}
+}
+
+// Exit1 is like Exit0, but returns t1 when e is nil.
+func Exit1[T1 any](t1 T1, e error) T1 {
+	Exit0(e)
+	return t1
+}
+
+// Exit2 is like Exit0, but returns (t1, t2) when e is nil.
+func Exit2[T1, T2 any](t1 T1, t2 T2, e error) (T1, T2) {
+	Exit0(e)
+	return t1, t2
+}
+
+// Exit3 is like Exit0, but returns (t1, t2, t3) when e is nil.
+func Exit3[T1, T2, T3 any](t1 T1, t2 T2, t3 T3, e error) (T1, T2, T3) {
+	Exit0(e)
+	return t1, t2, t3
+}
+
+// Exit4 is like Exit0, but returns (t1, t2, t3, t4) when e is nil.
+func Exit4[T1, T2, T3, T4 any](t1 T1, t2 T2, t3 T3, t4 T4, e error) (T1, T2, T3, T4) {
+	Exit0(e)
+	return t1, t2, t3, t4
+}
+
+// Exit5 is like Exit0, but returns (t1, t2, t3, t4, t5) when e is nil.
+func Exit5[T1, T2, T3, T4, T5 any](t1 T1, t2 T2, t3 T3, t4 T4, t5 T5, e error) (T1, T2, T3, T4, T5) {
+	Exit0(e)
+	return t1, t2, t3, t4, t5
+}

exitlog_test.go

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+// Copyright 2023 Patrick Smith
+// Use of this source code is subject to the MIT-style license in the LICENSE file.
+
+package or
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/pat42smith/gotest"
+)
+
+// Check that Exitn and Logn handle non-nil errors correctly.
+// This requires a separate process.
+
+var test_source = `package main
+
+import (
+	"errors"
+	"log"
+	"os"
+	"github.com/pat42smith/or"
+)
+
+func main() {
+	log.SetFlags(0)
+	log.SetPrefix("logged: ")
+
+	switch os.Args[1] {
+	case "exit":
+		switch os.Args[2] {
+		case "0":
+			or.Exit0(errors.New("zero"))
+		case "1":
+			or.Exit1(1, errors.New("one"))
+		case "2":
+			or.Exit2(1, 2, errors.New("two"))
+		case "3":
+			or.Exit3(1, 2, 3, errors.New("three"))
+		case "4":
+			or.Exit4(1, 2, 3, 4, errors.New("four"))
+		case "5":
+			or.Exit5(1, 2, 3, 4, 5, errors.New("five"))
+		}
+	case "log":
+		switch os.Args[2] {
+		case "0":
+			or.Log0(errors.New("zero"))
+		case "1":
+			or.Log1(1, errors.New("one"))
+		case "2":
+			or.Log2(1, 2, errors.New("two"))
+		case "3":
+			or.Log3(1, 2, 3, errors.New("three"))
+		case "4":
+			or.Log4(1, 2, 3, 4, errors.New("four"))
+		case "5":
+			or.Log5(1, 2, 3, 4, 5, errors.New("five"))
+		}
+	}
+}`
+
+func checkExitLog(t *testing.T, program, which, n, expect string) {
+	t.Helper()
+	cmd := gotest.Command(program, which, n)
+	cmd.WantStderr(expect + "\n")
+	cmd.WantCode(1)
+	cmd.Run(t, "")
+}
+
+func TestExitLog(t *testing.T) {
+	tmp := t.TempDir()
+	testgo := filepath.Join(tmp, "test.go")
+	testexe := filepath.Join(tmp, "test.exe")
+	if e := os.WriteFile(testgo, []byte(test_source), 0444); e != nil {
+		t.Fatal(e)
+	}
+	gotest.Command("go", "build", "-o", testexe, testgo).Run(t, "")
+
+	checkExitLog(t, testexe, "exit", "0", "zero")
+	checkExitLog(t, testexe, "exit", "1", "one")
+	checkExitLog(t, testexe, "exit", "2", "two")
+	checkExitLog(t, testexe, "exit", "3", "three")
+	checkExitLog(t, testexe, "exit", "4", "four")
+	checkExitLog(t, testexe, "exit", "5", "five")
+
+	checkExitLog(t, testexe, "log", "0", "logged: zero")
+	checkExitLog(t, testexe, "log", "1", "logged: one")
+	checkExitLog(t, testexe, "log", "2", "logged: two")
+	checkExitLog(t, testexe, "log", "3", "logged: three")
+	checkExitLog(t, testexe, "log", "4", "logged: four")
+	checkExitLog(t, testexe, "log", "5", "logged: five")
+}