Check errors by identity, not by message text, in tests (closes #49)

Tests that asserted a failure by a fragment of its message now use
errors.Is: a refactor returning the wrong error, or wrapping with %v
instead of %w, now fails them. New tests return each exported error of
internal/vault and pkg/bip85 that no test returned, and check wrapped
causes (os.ErrNotExist, ErrMnemonicMismatch through GetSecret,
ErrInvalidPathComponent through DeriveBIP85Entropy). The 999-versions
test moves into package secret to name its unexported error. Checks of
errors no test can name keep their text; they are listed on the issue.

Model: opus-5-5

internal/cli/integration_test.go

@@ -680,10 +680,10 @@ func test06GetSecret(t *testing.T, testMnemonic string, runSecret func(...string
 	require.NoError(t, err, "get secret should succeed")
 	assert.Equal(t, "password123", strings.TrimSpace(output), "should return correct secret value")
 
-	// Test that without mnemonic, we get an error
-	output, err = runSecret("get", "database/password")
-	require.Error(t, err, "get should fail without unlock method")
-	assert.Contains(t, output, "failed to unlock vault", "should indicate unlock failure")
+	// Test that without mnemonic, we get an error: the passphrase unlocker
+	// cannot ask for its passphrase, as the tests have no terminal
+	_, err = runSecret("get", "database/password")
+	require.ErrorIs(t, err, secret.ErrPassphraseNotRead, "get should fail without unlock method")
 }
 
 func test07AddSecretVersion(t *testing.T, tempDir, testMnemonic string, runSecret func(...string) (string, error), runSecretWithEnv func(map[string]string, ...string) (string, error), runSecretWithStdin func(string, map[string]string, ...string) (string, error)) {
@@ -839,12 +839,11 @@ func test09GetSpecificVersion(t *testing.T, tempDir, testMnemonic string, runSec
 	assert.Equal(t, "newpassword456", strings.TrimSpace(output), "should return new secret value without --version")
 
 	// An empty --version is not a version; it does not mean the current one
-	output, err = runSecretWithEnv(map[string]string{
+	_, err = runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "--version", "", "database/password")
 
-	require.Error(t, err, "get with an empty version should fail")
-	assert.Contains(t, output, "version '' not found", "should reject the empty version")
+	require.ErrorIs(t, err, vault.ErrVersionNotFound, "should reject the empty version")
 }
 
 func test10PromoteVersion(t *testing.T, tempDir, testMnemonic string, runSecret func(...string) (string, error), runSecretWithEnv func(map[string]string, ...string) (string, error)) {
@@ -1158,11 +1157,7 @@ func testInvalidSecretNames(t *testing.T, testMnemonic string, runSecretWithStdi
 			shouldFail := slices.Contains(definitelyInvalid, invalidName)
 
 			if shouldFail {
-				require.Error(t, err, "add '%s' should fail", invalidName)
-
-				if err != nil {
-					assert.Contains(t, output, "invalid secret name", "should indicate invalid name for '%s'", invalidName)
-				}
+				require.ErrorIs(t, err, vault.ErrInvalidSecretName, "add '%s' should fail", invalidName)
 			} else {
 				// For the slash cases and .hidden, they might succeed
 				// Just log what happened
@@ -1310,9 +1305,8 @@ func test12cCrossVaultMove(t *testing.T, testMnemonic string, runSecretWithEnv f
 	require.NoError(t, err, "add force/test in work should succeed")
 
 	// Move without force should fail
-	output, err = runSecretWithEnv(env, "move", "work:force/test", "default")
-	require.Error(t, err, "move without force should fail when dest exists")
-	assert.Contains(t, output, "already exists", "should indicate destination exists")
+	_, err = runSecretWithEnv(env, "move", "work:force/test", "default")
+	require.ErrorIs(t, err, vault.ErrSecretExists, "move without force should fail when dest exists")
 
 	// Move with force should succeed
 	output, err = runSecretWithEnv(env, "move", "--force", "work:force/test", "default")
@@ -1427,9 +1421,8 @@ func test14SwitchVault(t *testing.T, tempDir string, runSecret func(...string) (
 	require.NoError(t, err, "vault select default should succeed")
 
 	// Test selecting non-existent vault
-	output, err := runSecret("vault", "select", "nonexistent")
-	require.Error(t, err, "selecting non-existent vault should fail")
-	assert.Contains(t, output, "does not exist", "should indicate vault doesn't exist")
+	_, err = runSecret("vault", "select", "nonexistent")
+	require.ErrorIs(t, err, vault.ErrVaultNotFound, "selecting non-existent vault should fail")
 }
 
 func test15VaultIsolation(t *testing.T, testMnemonic string, runSecret func(...string) (string, error), runSecretWithEnv func(map[string]string, ...string) (string, error), runSecretWithStdin func(string, map[string]string, ...string) (string, error)) {
@@ -1450,11 +1443,10 @@ func test15VaultIsolation(t *testing.T, testMnemonic string, runSecret func(...s
 	require.NoError(t, err, "vault select work should succeed")
 
 	// Try to get the default-only secret (should fail)
-	output, err := runSecretWithEnv(map[string]string{
+	_, err = runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "default-only/secret")
-	require.Error(t, err, "should not be able to get default vault secret from work vault")
-	assert.Contains(t, output, "not found", "should indicate secret not found")
+	require.ErrorIs(t, err, vault.ErrSecretNotFound, "should not be able to get default vault secret from work vault")
 
 	// Add a unique secret to work vault
 	_, err = runSecretWithStdin("work-vault-secret", map[string]string{
@@ -1467,14 +1459,13 @@ func test15VaultIsolation(t *testing.T, testMnemonic string, runSecret func(...s
 	require.NoError(t, err, "vault select default should succeed")
 
 	// Try to get the work-only secret (should fail)
-	output, err = runSecretWithEnv(map[string]string{
+	_, err = runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "work-only/secret")
-	require.Error(t, err, "should not be able to get work vault secret from default vault")
-	assert.Contains(t, output, "not found", "should indicate secret not found")
+	require.ErrorIs(t, err, vault.ErrSecretNotFound, "should not be able to get work vault secret from default vault")
 
 	// Verify we can still get the default-only secret
-	output, err = runSecretWithEnv(map[string]string{
+	output, err := runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "default-only/secret")
 	require.NoError(t, err, "get default-only secret should succeed")
@@ -1586,11 +1577,10 @@ func test17ImportFromFile(t *testing.T, tempDir, testMnemonic string, runSecretW
 	// Just verify the import succeeded
 
 	// Test importing non-existent file
-	output, err = runSecretWithEnv(map[string]string{
+	_, err = runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "import", "imported/nonexistent", "--source", "/nonexistent/file")
-	require.Error(t, err, "importing non-existent file should fail")
-	assert.Contains(t, output, "failed", "should indicate failure")
+	require.ErrorIs(t, err, os.ErrNotExist, "importing non-existent file should fail")
 
 	// Verify filesystem structure
 	defaultVaultDir := filepath.Join(tempDir, "vaults.d", "default")
@@ -1905,11 +1895,10 @@ func test23ErrorHandling(t *testing.T, tempDir, secretPath, testMnemonic string,
 	t.Helper()
 
 	// Get non-existent secret
-	output, err := runSecretWithEnv(map[string]string{
+	_, err := runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "nonexistent/secret")
-	require.Error(t, err, "get non-existent secret should fail")
-	assert.Contains(t, output, "not found", "should indicate secret not found")
+	require.ErrorIs(t, err, vault.ErrSecretNotFound, "get non-existent secret should fail")
 
 	// Add secret without mnemonic or unlocker
 	unsetMnemonic := os.Getenv(secret.EnvMnemonic)
@@ -1939,13 +1928,12 @@ func test23ErrorHandling(t *testing.T, tempDir, secretPath, testMnemonic string,
 	// Invalid secret names (already tested in test 12)
 
 	// Non-existent vault operations
-	output, err = runSecret("vault", "select", "nonexistent")
-	require.Error(t, err, "select non-existent vault should fail")
-	assert.Contains(t, output, "does not exist", "should indicate vault doesn't exist")
+	_, err = runSecret("vault", "select", "nonexistent")
+	require.ErrorIs(t, err, vault.ErrVaultNotFound, "select non-existent vault should fail")
 
 	// Import to non-existent vault with test passphrase
 	testPassphrase := "test-passphrase-123" // Define testPassphrase locally
-	output, err = runSecretWithEnv(map[string]string{
+	output, err := runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic:         testMnemonic,
 		secret.EnvUnlockPassphrase: testPassphrase,
 	}, "vault", "import", "nonexistent")
@@ -1953,11 +1941,10 @@ func test23ErrorHandling(t *testing.T, tempDir, secretPath, testMnemonic string,
 	assert.Contains(t, output, "does not exist", "should indicate vault doesn't exist")
 
 	// Get specific version that doesn't exist
-	output, err = runSecretWithEnv(map[string]string{
+	_, err = runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "--version", "99999999.999", "database/password")
-	require.Error(t, err, "get non-existent version should fail")
-	assert.Contains(t, output, "not found", "should indicate version not found")
+	require.ErrorIs(t, err, vault.ErrVersionNotFound, "get non-existent version should fail")
 
 	// Promote non-existent version
 	output, err = runSecretWithEnv(map[string]string{
@@ -2367,11 +2354,10 @@ func test30BackupRestore(t *testing.T, tempDir, secretPath, testMnemonic string,
 	assert.NotEmpty(t, output, "restored secret should have value")
 
 	// Verify post-backup secret is gone
-	output, err = runSecretWithEnv(map[string]string{
+	_, err = runSecretWithEnv(map[string]string{
 		secret.EnvMnemonic: testMnemonic,
 	}, "get", "post-backup/secret")
-	require.Error(t, err, "post-backup secret should not exist after restore")
-	assert.Contains(t, output, "not found", "should indicate secret not found")
+	require.ErrorIs(t, err, vault.ErrSecretNotFound, "post-backup secret should not exist after restore")
 
 	t.Log("Backup and restore completed successfully")
 }
@@ -2436,8 +2422,7 @@ func test31EnvMnemonicUsesVaultDerivationIndex(t *testing.T, tempDir, secretPath
 		t.Logf("Output: %s", getOutput)
 
 		// This is the expected behavior with the current bug
-		require.Error(t, err, "get should fail due to wrong derivation index")
-		assert.Contains(t, getOutput, "derived public key does not match vault", "should indicate key derivation failure")
+		require.ErrorIs(t, err, vault.ErrMnemonicMismatch, "get should fail due to wrong derivation index")
 
 		// Document what should happen when the bug is fixed
 		t.Log("When the bug is fixed, GetValue should read vault metadata and use derivation index 1")