errdefs: add tests error conversions

Signed-off-by: Stephen J Day <stephen.day@docker.com>

errdefs/grpc_test.go

@@ -0,0 +1,65 @@
+package errdefs
+
+import (
+	"testing"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/codes"
+
+	"github.com/pkg/errors"
+)
+
+func TestGRPCRoundTrip(t *testing.T) {
+	errShouldLeaveAlone := errors.New("unknown to package")
+
+	for _, testcase := range []struct {
+		input error
+		cause error
+		str   string
+	}{
+		{
+			input: ErrAlreadyExists,
+			cause: ErrAlreadyExists,
+		},
+		{
+			input: ErrNotFound,
+			cause: ErrNotFound,
+		},
+		{
+			input: errors.Wrapf(ErrFailedPrecondition, "test test test"),
+			cause: ErrFailedPrecondition,
+			str:   "test test test: failed precondition",
+		},
+		{
+			input: grpc.Errorf(codes.Unavailable, "should be not available"),
+			cause: ErrUnavailable,
+			str:   "should be not available: unavailable",
+		},
+		{
+			input: errShouldLeaveAlone,
+			cause: ErrUnknown,
+			str:   errShouldLeaveAlone.Error() + ": " + ErrUnknown.Error(),
+		},
+	} {
+		t.Run(testcase.input.Error(), func(t *testing.T) {
+			t.Logf("input: %v", testcase.input)
+			gerr := ToGRPC(testcase.input)
+			t.Logf("grpc: %v", gerr)
+			ferr := FromGRPC(gerr)
+			t.Logf("recovered: %v", ferr)
+
+			if errors.Cause(ferr) != testcase.cause {
+				t.Fatalf("unexpected cause: %v != %v", errors.Cause(ferr), testcase.cause)
+			}
+
+			expected := testcase.str
+			if expected == "" {
+				expected = testcase.cause.Error()
+			}
+			if ferr.Error() != expected {
+				t.Fatalf("unexpected string: %q != %q", ferr.Error(), expected)
+			}
+		})
+	}
+
+}