100% test coverage

README.md

@@ -116,7 +116,7 @@ The publicid package generates and validates NanoID strings designed to be publi
 
 
 <a name="New"></a>
-## func [New](<https://github.com/agentstation/publicid/blob/master/publicid.go#L35>)
+## func [New](<https://github.com/agentstation/publicid/blob/master/publicid.go#L38>)
 
 ```go
 func New(opts ...Option) (string, error)
@@ -125,7 +125,7 @@ func New(opts ...Option) (string, error)
 New generates a unique nanoID with a length of 8 characters and the given options.
 
 <a name="NewLong"></a>
-## func [NewLong](<https://github.com/agentstation/publicid/blob/master/publicid.go#L40>)
+## func [NewLong](<https://github.com/agentstation/publicid/blob/master/publicid.go#L43>)
 
 ```go
 func NewLong(opts ...Option) (string, error)
@@ -134,7 +134,7 @@ func NewLong(opts ...Option) (string, error)
 NewLong generates a unique nanoID with a length of 12 characters and the given options.
 
 <a name="Validate"></a>
-## func [Validate](<https://github.com/agentstation/publicid/blob/master/publicid.go#L64>)
+## func [Validate](<https://github.com/agentstation/publicid/blob/master/publicid.go#L67>)
 
 ```go
 func Validate(id string) error
@@ -143,7 +143,7 @@ func Validate(id string) error
 Validate checks if a given field name's public ID value is valid according to the constraints defined by package publicid.
 
 <a name="ValidateLong"></a>
-## func [ValidateLong](<https://github.com/agentstation/publicid/blob/master/publicid.go#L70>)
+## func [ValidateLong](<https://github.com/agentstation/publicid/blob/master/publicid.go#L73>)
 
 ```go
 func ValidateLong(id string) error
@@ -152,7 +152,7 @@ func ValidateLong(id string) error
 validateLong checks if a given field name's public ID value is valid according to the constraints defined by package publicid.
 
 <a name="Option"></a>
-## type [Option](<https://github.com/agentstation/publicid/blob/master/publicid.go#L20>)
+## type [Option](<https://github.com/agentstation/publicid/blob/master/publicid.go#L23>)
 
 Option is a function type for configuring ID generation.
 
@@ -161,7 +161,7 @@ type Option func(*config)
 ```
 
 <a name="Attempts"></a>
-### func [Attempts](<https://github.com/agentstation/publicid/blob/master/publicid.go#L28>)
+### func [Attempts](<https://github.com/agentstation/publicid/blob/master/publicid.go#L31>)
 
 ```go
 func Attempts(n int) Option

publicid.go

@@ -16,6 +16,9 @@ const (
 	shortLen = 8
 )
 
+// generator is the function used to generate nanoIDs.
+var generator = nanoid.Generate
+
 // Option is a function type for configuring ID generation.
 type Option func(*config)
 
@@ -50,7 +53,7 @@ func generateID(length int, opts ...Option) (string, error) {
 
 	var lastErr error
 	for i := 0; i < cfg.attempts; i++ {
-		id, err := nanoid.Generate(alphabet, length)
+		id, err := generator(alphabet, length)
 		if err == nil {
 			return id, nil
 		}

publicid_test.go

@@ -4,6 +4,7 @@
 package publicid
 
 import (
+	"fmt"
 	"testing"
 )
 
@@ -104,3 +105,27 @@ func TestValidateLong(t *testing.T) {
 		})
 	}
 }
+
+func TestNewFailsAfterAttempts(t *testing.T) {
+
+	// generator functions for testing
+	nanoIDGenerator := generator
+	mockGenerator := func(alphabet string, size int) (string, error) {
+		return "", fmt.Errorf("mocked error")
+	}
+
+	// Replace the Generate function with our mock generator function,
+	// and restore the original generator function in the deferred function.
+	generator = mockGenerator
+	defer func() { generator = nanoIDGenerator }()
+
+	_, err := New(Attempts(3))
+	if err == nil {
+		t.Error("Expected an error, but got nil")
+	} else {
+		expectedErrMsg := "failed to generate ID after 3 attempts: mocked error"
+		if err.Error() != expectedErrMsg {
+			t.Errorf("Expected error message '%s', but got '%s'", expectedErrMsg, err.Error())
+		}
+	}
+}