mfer/internal/cli/errmsg_test.go

//nolint:testpackage // white-box tests exercise unexported internals
package cli

import (
	"fmt"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// errMsgCase is one pinned user-visible error message.
type errMsgCase struct {
	name string
	err  error
	want string
}

const (
	msgFpA = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA"
	msgFpB = "BBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBB"
)

func checkErrMsgCases(t *testing.T, cases []errMsgCase) {
	t.Helper()

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			assert.Equal(t, tc.want, tc.err.Error())
		})
	}
}

// TestErrorMessagesVerbatim pins the exact rendered text of the CLI's
// user-visible error messages.
//
// These strings are an interface: they are grepped for in CI pipelines
// and quoted in bug reports. The messages are assembled by wrapping
// static sentinels, and it is easy to change what a user sees while
// only meaning to make an error matchable with errors.Is - which is
// precisely what happened once already. Any change to a string below is
// therefore a deliberate, separately stated change, never a side effect
// of a refactor.
func TestErrorMessagesVerbatim(t *testing.T) {
	t.Parallel()

	checkErrMsgCases(t, []errMsgCase{
		{
			name: "check: no manifest found",
			err: fmt.Errorf("%w in %s (looked for index.mf and .index.mf)",
				errNoManifestFound, "/tmp/x"),
			want: "no manifest found in /tmp/x " +
				"(looked for index.mf and .index.mf)",
		},
		{
			name: "check: invalid fingerprint length",
			err:  fmt.Errorf("%w, got %d", errInvalidFingerprint, 8),
			want: "invalid fingerprint: must be exactly 40 hex characters, got 8",
		},
		{
			name: "check: manifest not signed",
			err: fmt.Errorf("%w, but signature from %s is required",
				errManifestNotSigned, msgFpA),
			want: "manifest is not signed, but signature from " + msgFpA +
				" is required",
		},
		{
			name: "check: signer mismatch",
			err: fmt.Errorf("embedded signing key fingerprint %s %w %s",
				msgFpA, errSignerMismatch, msgFpB),
			want: "embedded signing key fingerprint " + msgFpA +
				" does not match required " + msgFpB,
		},
		{
			name: "gen: path does not exist",
			err:  fmt.Errorf("%w: %s", errPathNotExist, "nope"),
			want: "path does not exist: nope",
		},
		{
			name: "gen: output file exists",
			err:  fmt.Errorf("output file %s %w", "index.mf", errOutputExists),
			want: "output file index.mf already exists " +
				"(use --force to overwrite)",
		},
		{
			name: "mfer: unknown command",
			err:  fmt.Errorf("%w %q", errUnknownCommand, "bogus"),
			want: `unknown command "bogus"`,
		},
	})
}

// TestFetchErrorMessagesVerbatim pins the fetch and manifest-loader
// messages; see TestErrorMessagesVerbatim for why.
func TestFetchErrorMessagesVerbatim(t *testing.T) {
	t.Parallel()

	checkErrMsgCases(t, []errMsgCase{
		{
			name: "manifest_loader: http status",
			err: fmt.Errorf("failed to fetch %s: %w %d",
				"https://example.com/index.mf", errHTTPStatus, 404),
			want: "failed to fetch https://example.com/index.mf: HTTP 404",
		},
		{
			name: "fetch: manifest http status",
			err: fmt.Errorf("failed to fetch manifest: %w %d",
				errHTTPStatus, 404),
			want: "failed to fetch manifest: HTTP 404",
		},
		{
			name: "fetch: file http status",
			err:  fmt.Errorf("%w %d", errHTTPStatus, 500),
			want: "HTTP 500",
		},
		{
			name: "fetch: empty path",
			err:  errEmptyPath,
			want: "empty path",
		},
		{
			name: "fetch: absolute path",
			err:  fmt.Errorf("%w: %s", errAbsolutePath, "/etc/passwd"),
			want: "absolute path not allowed: /etc/passwd",
		},
		{
			name: "fetch: path traversal",
			err:  fmt.Errorf("%w: %s", errPathTraversal, "../x"),
			want: "path traversal not allowed: ../x",
		},
		{
			name: "fetch: size mismatch",
			err: fmt.Errorf("%w: expected %d bytes, got %d",
				errSizeMismatch, 10, 9),
			want: "size mismatch: expected 10 bytes, got 9",
		},
		{
			name: "fetch: url required",
			err:  errURLRequired,
			want: "URL argument required",
		},
		{
			name: "fetch: hash mismatch",
			err:  errHashMismatch,
			want: "hash mismatch",
		},
	})
}

// TestSentinelsAreMatchable checks that the wrapped forms of the
// messages above remain matchable with errors.Is, which is the reason
// the sentinels exist at all.
func TestSentinelsAreMatchable(t *testing.T) {
	t.Parallel()

	wrapped := fmt.Errorf("embedded signing key fingerprint %s %w %s",
		"a", errSignerMismatch, "b")
	require.ErrorIs(t, wrapped, errSignerMismatch)

	wrapped = fmt.Errorf("output file %s %w", "index.mf", errOutputExists)
	require.ErrorIs(t, wrapped, errOutputExists)

	wrapped = fmt.Errorf("failed to fetch manifest: %w %d", errHTTPStatus, 404)
	require.ErrorIs(t, wrapped, errHTTPStatus)

	assert.NotErrorIs(t, errHashMismatch, errSizeMismatch)
}