Add internal/assert package

go.sum

@@ -4,6 +4,7 @@ github.com/atotto/clipboard v0.0.0-20171229224153-bc5958e1c833 h1:h/E5ryZTJAtOY6
 github.com/atotto/clipboard v0.0.0-20171229224153-bc5958e1c833/go.mod h1:ZY9tmq7sm5xIbd9bOK4onWV4S6X0u6GY7Vn0Yu86PYI=
 github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869 h1:DDGfHa7BWjL4YnC6+E63dPcxHo2sUxDIu8g3QgEJdRY=
 github.com/bmizerany/assert v0.0.0-20160611221934-b7ed37b82869/go.mod h1:Ekp36dRnpXw/yCqJaO+ZrUyxD+3VXMFFr56k5XYrpB4=
+github.com/google/go-cmp v0.4.0 h1:xsAVV57WRhGj6kEIi8ReJzQlHHqcBYCElAvkovg3B/4=
 github.com/kballard/go-shellquote v0.0.0-20170619183022-cd60e84ee657 h1:vE7J1m7cCpiRVEIr1B5ccDxRpbPsWT5JU3if2Di5nE4=
 github.com/kballard/go-shellquote v0.0.0-20170619183022-cd60e84ee657/go.mod h1:CzGEWj7cYgsdH8dAjBGEr58BoE7ScuLd+fwFZ44+/x8=
 github.com/kr/pretty v0.0.0-20160823170715-cfb55aafdaf3 h1:dhwb1Ev84SKKVBfLuhR4bw/29yYHzwtTyTLUWWnvYxI=

internal/assert/assert.go

+// Package assert provides functions for testing.
+package assert
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+// Equal makes the test as failed using default formatting if got is not equal to want.
+func Equal(t testing.TB, want, got interface{}, args ...interface{}) {
+	t.Helper()
+	if !reflect.DeepEqual(want, got) {
+		msg := fmt.Sprint(args...)
+		t.Errorf("%s\n%s", msg, cmp.Diff(want, got))
+	}
+}
+
+// NotEqual makes the test as failed using default formatting if got is equal to want.
+func NotEqual(t testing.TB, want, got interface{}, args ...interface{}) {
+	t.Helper()
+	if reflect.DeepEqual(want, got) {
+		msg := fmt.Sprint(args...)
+		t.Errorf("%s\nUnexpected: <%#v>", msg, want)
+	}
+}
+
+// T makes the test as failed using default formatting if ok is false.
+func T(t testing.TB, ok bool, args ...interface{}) {
+	t.Helper()
+	if !ok {
+		msg := fmt.Sprint(args...)
+		t.Errorf("%s\nFailure", msg)
+	}
+}