more tests and standardize struct field casing

README.md

@@ -1,3 +1,5 @@
 # go-openlibrary
 
-A simple Go wrapper around the OpenLibrary.org Books API: <https://openlibrary.org/dev/docs/api/books>.
+[![Go Reference](https://pkg.go.dev/badge/git.yetaga.in/alazyreader/go-openlibrary.svg)](https://pkg.go.dev/git.yetaga.in/alazyreader/go-openlibrary)
+
+A simple Go wrapper around the OpenLibrary.org **Books** API: <https://openlibrary.org/dev/docs/api/books>.

client/client.go

@@ -12,7 +12,16 @@ var (
 	defaultAPI = "https://openlibrary.org/api/books"
 )
 
-// Client
+var (
+	// FormatError marks errors with provided book identifers
+	FormatError = fmt.Errorf("identifier in wrong format")
+	// NetworkError marks errors with the connection to the OpenLibrary API
+	NetworkError = fmt.Errorf("network error")
+	// NotFoundError marks an empty response from the OpenLibrary API
+	NotFoundError = fmt.Errorf("book not found")
+)
+
+// Client provides OpenLibrary Books API query methods
 type Client struct {
 	httpClient http.Client
 	apipath    string
@@ -33,9 +42,9 @@ func (c *Client) SetAPIPath(p string) {
 // GetByISBN fetches details for a book based on its ISBN10 or ISBN13.
 func (c *Client) GetByISBN(k string) (*BookDetails, error) {
 	if k == "" {
-		return nil, fmt.Errorf("ISBN cannot be empty")
+		return nil, fmt.Errorf("%w: ISBN cannot be empty", FormatError)
 	} else if len(k) != 10 && len(k) != 13 {
-		return nil, fmt.Errorf("ISBN must be either 10 or 13 digits")
+		return nil, fmt.Errorf("%w: ISBN must be either 10 or 13 digits", FormatError)
 	}
 	key := "ISBN:" + k
 	return c.fetch(key)
@@ -44,7 +53,7 @@ func (c *Client) GetByISBN(k string) (*BookDetails, error) {
 // GetByOCLC fetches details for a book based on its WorldCat OCLC number.
 func (c *Client) GetByOCLC(k string) (*BookDetails, error) {
 	if k == "" {
-		return nil, fmt.Errorf("OCLC cannot be empty")
+		return nil, fmt.Errorf("%w: OCLC cannot be empty", FormatError)
 	}
 	key := "OCLC:" + k
 	return c.fetch(key)
@@ -53,7 +62,7 @@ func (c *Client) GetByOCLC(k string) (*BookDetails, error) {
 // GetByLCCN fetches details for a book based on its Library of Congress Control Number.
 func (c *Client) GetByLCCN(k string) (*BookDetails, error) {
 	if k == "" {
-		return nil, fmt.Errorf("LCCN cannot be empty")
+		return nil, fmt.Errorf("%w: LCCN cannot be empty", FormatError)
 	}
 	key := "LCCN:" + k
 	return c.fetch(key)
@@ -62,7 +71,7 @@ func (c *Client) GetByLCCN(k string) (*BookDetails, error) {
 // GetByOLID fetches details for a book based on its OpenLibrary ID number.
 func (c *Client) GetByOLID(k string) (*BookDetails, error) {
 	if k == "" {
-		return nil, fmt.Errorf("OLID cannot be empty")
+		return nil, fmt.Errorf("%w: OLID cannot be empty", FormatError)
 	}
 	key := "OLID:" + k
 	return c.fetch(key)
@@ -82,7 +91,7 @@ func (c *Client) fetch(key string) (*BookDetails, error) {
 	}
 	u, err := url.Parse(h)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%w: %v", NetworkError, err)
 	}
 	u.RawQuery = url.Values{
 		"bibkeys": []string{key},
@@ -92,26 +101,26 @@ func (c *Client) fetch(key string) (*BookDetails, error) {
 
 	resp, err := c.httpClient.Get(u.String())
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%w: %v", NetworkError, err)
 	}
 	defer resp.Body.Close()
 
 	if resp.StatusCode != http.StatusOK {
-		return nil, fmt.Errorf("received non-200 status code: %d", resp.StatusCode)
+		return nil, fmt.Errorf("%w: received non-200 status code: %d", NetworkError, resp.StatusCode)
 	}
 
 	var result response
 	b, err := io.ReadAll(resp.Body)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%w: %v", NetworkError, err)
 	}
 	if err = json.Unmarshal(b, &result); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("%w: %v", NetworkError, err)
 	}
 
 	details, ok := result[key]
 	if !ok {
-		return nil, fmt.Errorf("book not found")
+		return nil, NotFoundError
 	}
 
 	return &details, nil

client/client_test.go

@@ -1,6 +1,7 @@
 package client
 
 import (
+	"errors"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -9,7 +10,10 @@ import (
 
 func testServer(expectedkey string) *httptest.Server {
 	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.URL.Query().Get("bibkeys") == expectedkey {
+		if r.URL.Query().Get("bibkeys") == "SPECIAL:MISSING" {
+			w.WriteHeader(http.StatusOK)
+			w.Write([]byte("{}"))
+		} else if r.URL.Query().Get("bibkeys") == expectedkey {
 			w.WriteHeader(http.StatusOK)
 			w.Write([]byte(fmt.Sprintf(exampleResponse, expectedkey)))
 		} else {
@@ -34,6 +38,7 @@ func TestFetch(t *testing.T) {
 		t.Fail()
 	}
 }
+
 func TestFetchFailure(t *testing.T) {
 	r := testServer("ISBN:1234567890")
 	defer r.Close()
@@ -41,12 +46,72 @@ func TestFetchFailure(t *testing.T) {
 	c := Client{}
 	c.SetAPIPath(r.URL)
 	_, err := c.GetByISBN("9780980200447")
-	if err == nil {
-		t.Log("expected error, received nil")
+	if err == nil || !errors.Is(err, NetworkError) {
+		t.Logf("expected error, received nil: %v", err)
+		t.Fail()
+	}
+}
+
+func TestBookNotFound(t *testing.T) {
+	r := testServer("")
+	defer r.Close()
+
+	c := Client{}
+	c.SetAPIPath(r.URL)
+	_, err := c.GetByRawKey("SPECIAL:MISSING")
+	if err == nil || !errors.Is(err, NotFoundError) {
+		t.Logf("expected error, received nil: %v", err)
 		t.Fail()
 	}
 }
 
+func TestKeyRejections(t *testing.T) {
+	c := Client{}
+	cases := map[string][]string{
+		"ISBN": {"", "1", "12", "123", "1234", "12345", "123456", "1234567", "12345678", "123456789", "12345678901", "123456789012", "12345678901234"},
+		"OCLC": {""},
+		"LCCN": {""},
+		"OLID": {""},
+	}
+	for id, ts := range cases {
+		switch id {
+		case "ISBN":
+			for i := range ts {
+				_, err := c.GetByISBN(ts[i])
+				if !errors.Is(err, FormatError) {
+					t.Logf("%s received %v, expected %v", id, err, FormatError)
+					t.Fail()
+				}
+			}
+		case "OCLC":
+			for i := range ts {
+				_, err := c.GetByOCLC(ts[i])
+				if !errors.Is(err, FormatError) {
+					t.Logf("%s received %v, expected %v", id, err, FormatError)
+					t.Fail()
+				}
+			}
+		case "LCCN":
+			for i := range ts {
+				_, err := c.GetByLCCN(ts[i])
+				if !errors.Is(err, FormatError) {
+					t.Logf("%s received %v, expected %v", id, err, FormatError)
+					t.Fail()
+				}
+			}
+		case "OLID":
+			for i := range ts {
+				_, err := c.GetByOLID(ts[i])
+				if !errors.Is(err, FormatError) {
+					t.Logf("%s received %v, expected %v", id, err, FormatError)
+					t.Fail()
+				}
+			}
+		}
+	}
+}
+
+// example comes from the official API docs
 var exampleResponse = `{
     "%s": {
         "publishers": [

client/response.go

@@ -44,11 +44,11 @@ type Identifiers struct {
 	Amazon           []string `json:"amazon"`
 	Goodreads        []string `json:"goodreads"`
 	Google           []string `json:"google"`
-	Isbn10           []string `json:"isbn_10"`
-	Isbn13           []string `json:"isbn_13"`
-	Lccn             []string `json:"lccn"`
-	Librarything     []string `json:"librarything"`
-	Oclc             []string `json:"oclc"`
+	ISBN10           []string `json:"isbn_10"`
+	ISBN13           []string `json:"isbn_13"`
+	LCCN             []string `json:"lccn"`
+	LibraryThing     []string `json:"librarything"`
+	OCLC             []string `json:"oclc"`
 	ProjectGutenberg []string `json:"project_gutenberg"`
 }