Support new GitHub v3 API calendar-based versioning (#2581)

Fixes: #2580.

README.md

@@ -332,6 +332,40 @@ Preview functionality may take the form of entire methods or simply additional
 data returned from an otherwise non-preview method. Refer to the GitHub API
 documentation for details on preview functionality.
 
+### Calendar Versioning ###
+
+As of 2022-11-28, GitHub [has announced](https://github.blog/2022-11-28-to-infinity-and-beyond-enabling-the-future-of-githubs-rest-api-with-api-versioning/)
+that they are starting to version their v3 API based on "calendar-versioning".
+
+In practice, our goal is to make per-method version overrides (at
+least in the core library) rare and temporary.
+
+Our understanding of the GitHub docs is that they will be revving the
+entire API to each new date-based version, even if only a few methods
+have breaking changes. Other methods will accept the new version with
+their existing functionality. So when a new date-based version of the
+GitHub API is released, we (the repo maintainers) plan to:
+
+* update each method that had breaking changes, overriding their
+  per-method API version header. This may happen in one or multiple
+  commits and PRs, and is all done in the main branch.
+
+* once all of the methods with breaking changes have been updated,
+  have a final commit that bumps the default API version, and remove
+  all of the per-method overrides. That would now get a major version
+  bump when the next go-github release is made.
+
+### Version Compatibility Table ###
+
+The following table identifies which version of the GitHub API is
+supported by this (and past) versions of this repo (go-github).
+Versions prior to 48.2.0 are not listed.
+
+| go-github Version | GitHub v3 API Version |
+| ----------------- | --------------------- |
+| 48.2.0            | 2022-11-28            |
+
+
 ## License ##
 
 This library is distributed under the BSD-style license found in the [LICENSE](./LICENSE)

github/github.go

@@ -27,12 +27,14 @@ import (
 )
 
 const (
-	Version = "v48.0.0"
+	Version = "v48.2.0"
 
-	defaultBaseURL   = "https://api.github.com/"
-	defaultUserAgent = "go-github" + "/" + Version
-	uploadBaseURL    = "https://uploads.github.com/"
+	defaultAPIVersion = "2022-11-28"
+	defaultBaseURL    = "https://api.github.com/"
+	defaultUserAgent  = "go-github" + "/" + Version
+	uploadBaseURL     = "https://uploads.github.com/"
 
+	headerAPIVersion    = "X-GitHub-Api-Version"
 	headerRateLimit     = "X-RateLimit-Limit"
 	headerRateRemaining = "X-RateLimit-Remaining"
 	headerRateReset     = "X-RateLimit-Reset"
@@ -392,12 +394,24 @@ func NewEnterpriseClient(baseURL, uploadURL string, httpClient *http.Client) (*C
 	return c, nil
 }
 
+// RequestOption represents an option that can modify an http.Request.
+type RequestOption func(req *http.Request)
+
+// WithVersion overrides the GitHub v3 API version for this individual request.
+// For more information, see:
+// https://github.blog/2022-11-28-to-infinity-and-beyond-enabling-the-future-of-githubs-rest-api-with-api-versioning/
+func WithVersion(version string) RequestOption {
+	return func(req *http.Request) {
+		req.Header.Set(headerAPIVersion, version)
+	}
+}
+
 // NewRequest creates an API request. A relative URL can be provided in urlStr,
 // in which case it is resolved relative to the BaseURL of the Client.
 // Relative URLs should always be specified without a preceding slash. If
 // specified, the value pointed to by body is JSON encoded and included as the
 // request body.
-func (c *Client) NewRequest(method, urlStr string, body interface{}) (*http.Request, error) {
+func (c *Client) NewRequest(method, urlStr string, body interface{}, opts ...RequestOption) (*http.Request, error) {
 	if !strings.HasSuffix(c.BaseURL.Path, "/") {
 		return nil, fmt.Errorf("BaseURL must have a trailing slash, but %q does not", c.BaseURL)
 	}
@@ -430,14 +444,20 @@ func (c *Client) NewRequest(method, urlStr string, body interface{}) (*http.Requ
 	if c.UserAgent != "" {
 		req.Header.Set("User-Agent", c.UserAgent)
 	}
+	req.Header.Set(headerAPIVersion, defaultAPIVersion)
+
+	for _, opt := range opts {
+		opt(req)
+	}
+
 	return req, nil
 }
 
 // NewFormRequest creates an API request. A relative URL can be provided in urlStr,
 // in which case it is resolved relative to the BaseURL of the Client.
 // Relative URLs should always be specified without a preceding slash.
 // Body is sent with Content-Type: application/x-www-form-urlencoded.
-func (c *Client) NewFormRequest(urlStr string, body io.Reader) (*http.Request, error) {
+func (c *Client) NewFormRequest(urlStr string, body io.Reader, opts ...RequestOption) (*http.Request, error) {
 	if !strings.HasSuffix(c.BaseURL.Path, "/") {
 		return nil, fmt.Errorf("BaseURL must have a trailing slash, but %q does not", c.BaseURL)
 	}
@@ -457,13 +477,19 @@ func (c *Client) NewFormRequest(urlStr string, body io.Reader) (*http.Request, e
 	if c.UserAgent != "" {
 		req.Header.Set("User-Agent", c.UserAgent)
 	}
+	req.Header.Set(headerAPIVersion, defaultAPIVersion)
+
+	for _, opt := range opts {
+		opt(req)
+	}
+
 	return req, nil
 }
 
 // NewUploadRequest creates an upload request. A relative URL can be provided in
 // urlStr, in which case it is resolved relative to the UploadURL of the Client.
 // Relative URLs should always be specified without a preceding slash.
-func (c *Client) NewUploadRequest(urlStr string, reader io.Reader, size int64, mediaType string) (*http.Request, error) {
+func (c *Client) NewUploadRequest(urlStr string, reader io.Reader, size int64, mediaType string, opts ...RequestOption) (*http.Request, error) {
 	if !strings.HasSuffix(c.UploadURL.Path, "/") {
 		return nil, fmt.Errorf("UploadURL must have a trailing slash, but %q does not", c.UploadURL)
 	}
@@ -485,6 +511,12 @@ func (c *Client) NewUploadRequest(urlStr string, reader io.Reader, size int64, m
 	req.Header.Set("Content-Type", mediaType)
 	req.Header.Set("Accept", mediaTypeV3)
 	req.Header.Set("User-Agent", c.UserAgent)
+	req.Header.Set(headerAPIVersion, defaultAPIVersion)
+
+	for _, opt := range opts {
+		opt(req)
+	}
+
 	return req, nil
 }
 
@@ -1358,8 +1390,8 @@ func formatRateReset(d time.Duration) string {
 
 // When using roundTripWithOptionalFollowRedirect, note that it
 // is the responsibility of the caller to close the response body.
-func (c *Client) roundTripWithOptionalFollowRedirect(ctx context.Context, u string, followRedirects bool) (*http.Response, error) {
-	req, err := c.NewRequest("GET", u, nil)
+func (c *Client) roundTripWithOptionalFollowRedirect(ctx context.Context, u string, followRedirects bool, opts ...RequestOption) (*http.Response, error) {
+	req, err := c.NewRequest("GET", u, nil, opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -1380,7 +1412,7 @@ func (c *Client) roundTripWithOptionalFollowRedirect(ctx context.Context, u stri
 	if followRedirects && resp.StatusCode == http.StatusMovedPermanently {
 		resp.Body.Close()
 		u = resp.Header.Get("Location")
-		resp, err = c.roundTripWithOptionalFollowRedirect(ctx, u, false)
+		resp, err = c.roundTripWithOptionalFollowRedirect(ctx, u, false, opts...)
 	}
 	return resp, err
 }

github/github_test.go

@@ -517,6 +517,17 @@ func TestNewRequest(t *testing.T) {
 	if !strings.Contains(userAgent, Version) {
 		t.Errorf("NewRequest() User-Agent should contain %v, found %v", Version, userAgent)
 	}
+
+	apiVersion := req.Header.Get(headerAPIVersion)
+	if got, want := apiVersion, defaultAPIVersion; got != want {
+		t.Errorf("NewRequest() %v header is %v, want %v", headerAPIVersion, got, want)
+	}
+
+	req, _ = c.NewRequest("GET", inURL, inBody, WithVersion("2022-11-29"))
+	apiVersion = req.Header.Get(headerAPIVersion)
+	if got, want := apiVersion, "2022-11-29"; got != want {
+		t.Errorf("NewRequest() %v header is %v, want %v", headerAPIVersion, got, want)
+	}
 }
 
 func TestNewRequest_invalidJSON(t *testing.T) {
@@ -626,6 +637,17 @@ func TestNewFormRequest(t *testing.T) {
 	if got, want := req.Header.Get("User-Agent"), c.UserAgent; got != want {
 		t.Errorf("NewFormRequest() User-Agent is %v, want %v", got, want)
 	}
+
+	apiVersion := req.Header.Get(headerAPIVersion)
+	if got, want := apiVersion, defaultAPIVersion; got != want {
+		t.Errorf("NewRequest() %v header is %v, want %v", headerAPIVersion, got, want)
+	}
+
+	req, _ = c.NewFormRequest(inURL, inBody, WithVersion("2022-11-29"))
+	apiVersion = req.Header.Get(headerAPIVersion)
+	if got, want := apiVersion, "2022-11-29"; got != want {
+		t.Errorf("NewRequest() %v header is %v, want %v", headerAPIVersion, got, want)
+	}
 }
 
 func TestNewFormRequest_badURL(t *testing.T) {
@@ -680,6 +702,22 @@ func TestNewFormRequest_errorForNoTrailingSlash(t *testing.T) {
 	}
 }
 
+func TestNewUploadRequest_WithVersion(t *testing.T) {
+	c := NewClient(nil)
+	req, _ := c.NewUploadRequest("https://example.com/", nil, 0, "")
+
+	apiVersion := req.Header.Get(headerAPIVersion)
+	if got, want := apiVersion, defaultAPIVersion; got != want {
+		t.Errorf("NewRequest() %v header is %v, want %v", headerAPIVersion, got, want)
+	}
+
+	req, _ = c.NewUploadRequest("https://example.com/", nil, 0, "", WithVersion("2022-11-29"))
+	apiVersion = req.Header.Get(headerAPIVersion)
+	if got, want := apiVersion, "2022-11-29"; got != want {
+		t.Errorf("NewRequest() %v header is %v, want %v", headerAPIVersion, got, want)
+	}
+}
+
 func TestNewUploadRequest_badURL(t *testing.T) {
 	c := NewClient(nil)
 	_, err := c.NewUploadRequest(":", nil, 0, "")