Add assertion package.

assert/assert.go

@@ -0,0 +1,103 @@
+// Package assert provides C-like assertions for Go. For more
+// information, see assert(3) (e.g. `man 3 assert`).
+package assert
+
+import (
+	"fmt"
+	"os"
+	"runtime"
+	"testing"
+)
+
+// NoDebug, if set to true, will cause all asserts to be ignored.
+var NoDebug bool
+
+func die(what string) {
+	_, file, line, ok := runtime.Caller(2)
+	if !ok {
+		panic(what)
+	} else {
+		fmt.Fprintf(os.Stderr, "%s\n", what)
+		fmt.Fprintf(os.Stderr, "\t%s line %d\n", file, line)
+		os.Exit(1)
+	}
+}
+
+// Bool asserts that cond is false.
+func Bool(cond bool) {
+	if NoDebug {
+		return
+	}
+
+	if !cond {
+		die("assert.Bool failed")
+	}
+}
+
+// Error asserts that err is nil.
+func Error(err error) {
+	if NoDebug {
+		return
+	}
+
+	if nil != err {
+		die(err.Error())
+	}
+}
+
+// Error2 asserts that the actual error is the expected error.
+func Error2(expected, actual error) {
+	if NoDebug || (expected == actual) {
+		return
+	}
+
+	if expected == nil {
+		die(fmt.Sprintf("assert.Error2: %s", actual.Error()))
+	}
+
+	var should string
+	if actual == nil {
+		should = "no error was returned"
+	} else {
+		should = fmt.Sprintf("have '%s'", actual)
+	}
+
+	die(fmt.Sprintf("assert.Error2: expected '%s', but %s", expected, should))
+}
+
+// BoolT checks a boolean condition, calling Fatal on t if it is
+// false.
+func BoolT(t *testing.T, cond bool) {
+	if !cond {
+		t.Fatal("assert.Bool failed")
+	}
+}
+
+// ErrorT checks whether the error is nil, calling Fatal on t if it
+// isn't.
+func ErrorT(t *testing.T, err error) {
+	if nil != err {
+		t.Fatalf("%s", err)
+	}
+}
+
+// Error2T compares a pair of errors, calling Fatal on it if they
+// don't match.
+func Error2T(t *testing.T, expected, actual error) {
+	if NoDebug || (expected == actual) {
+		return
+	}
+
+	if expected == nil {
+		die(fmt.Sprintf("assert.Error2: %s", actual.Error()))
+	}
+
+	var should string
+	if actual == nil {
+		should = "no error was returned"
+	} else {
+		should = fmt.Sprintf("have '%s'", actual)
+	}
+
+	die(fmt.Sprintf("assert.Error2: expected '%s', but %s", expected, should))
+}