feat: GitHub Enterprise support

Added support for GitHub Enterprise. The additional properties `ghBaseUrl` and `ghApi` can be used to point to a GitHub Enterprise server.

src/main/groovy/de/gliderpilot/gradle/semanticrelease/GithubRepo.groovy

@@ -21,6 +21,11 @@ import groovy.transform.Memoized
 import groovy.transform.PackageScope
 import org.ajoberstar.grgit.Grgit
 
+import javax.ws.rs.core.HttpHeaders;
+import javax.ws.rs.core.MediaType;
+import com.jcabi.http.request.ApacheRequest;
+import com.jcabi.http.wire.AutoRedirectingWire;
+
 import java.util.regex.Matcher
 
 class GithubRepo extends GitRepo {
@@ -29,34 +34,69 @@ class GithubRepo extends GitRepo {
 
     private Github github
 
+    private String ghBaseUrl
+
+    private String ghApi
+
+    private String ghToken
+
     @PackageScope
     Github getGithub() {
         github
     }
 
     GithubRepo(Grgit grgit) {
+        this.ghBaseUrl = "https://github.com"
         this.grgit = grgit
     }
 
-    void setGhToken(String token) {
-        if (token)
-            github = new RtGithub(token)
+    void setGhBaseUrl(String ghBaseUrl) {
+      this.ghBaseUrl = ghBaseUrl.replaceAll("/+\$", "") // remove trailing slashes
+    }
+
+    void setGhApi(String githubApi) {
+      this.ghApi = githubApi.replaceAll("/+\$", "") // remove trailing slashes
+      github = buildGithubReference()
+    }
+
+    void setGhToken(String githubToken) {
+      this.ghToken = githubToken
+      github = buildGithubReference()
     }
 
     @PackageScope
     @Memoized
     String getMnemo() {
         String repositoryUrl = grgit.remote.list().find { it.name == 'origin' }.url
-        Matcher matcher = repositoryUrl =~ /.*github.com[\/:]((?:.+?)\/(?:.+?))(?:\.git)/
+        Matcher matcher = repositoryUrl =~ /.*[\/:](.*\/.*)(?:\.git)$/
         if (!matcher)
             return null
         return matcher.group(1)
     }
 
+    private RtGithub buildGithubReference() {
+      if (this.ghApi != null) { // for github enterprise repositories
+        def request = new ApacheRequest(this.ghApi)
+          .header(HttpHeaders.USER_AGENT, RtGithub.USER_AGENT)
+          .header(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON)
+          .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON)
+
+        if (this.ghToken != null) { // also add authentication token, if available
+          request = request.header(HttpHeaders.AUTHORIZATION, "token ${ghToken}")
+        }
+
+        request = request.through(AutoRedirectingWire.class)
+
+        return new RtGithub(request)
+      } else if (this.ghToken) { // for github.com repositories
+        return new RtGithub(this.ghToken)
+      }
+    }
+
     private String repositoryUrl(String suffix) {
         if (!mnemo)
             return null
-        return "https://github.com/${mnemo}/$suffix"
+        return "${ghBaseUrl}/${mnemo}/$suffix"
     }
 
     String diffUrl(String previousTag, String currentTag) {
@@ -71,4 +111,4 @@ class GithubRepo extends GitRepo {
         repositoryUrl("commit/${abbreviatedId}")
     }
 
-}
+}

src/test/groovy/de/gliderpilot/gradle/semanticrelease/GithubRepoSpec.groovy

@@ -29,7 +29,11 @@ class GithubRepoSpec extends Specification {
 
     @Shared
     @Subject
-    GithubRepo repo = new GithubRepo(grgit)
+    GithubRepo repo
+
+    def setup() {
+      repo = new GithubRepo(grgit)
+    }
 
     def "creates github service upon setting ghToken"() {
         when:
@@ -39,6 +43,33 @@ class GithubRepoSpec extends Specification {
         repo.github instanceof RtGithub
     }
 
+    def "creates github service upon setting ghToken with api endpoint"() {
+        when:
+        repo.ghToken = '12345'
+        repo.ghApi = 'https://github.enterprise/api/v3'
+
+        then:
+        repo.github instanceof RtGithub
+        repo.github.entry().uri.equals("https://github.enterprise/api/v3")
+    }
+
+    @Unroll
+    def "diffUrl for #tag1 and #tag2 is #expectedUrl when setting ghBaseUrl"() {
+        when:
+        repo.ghBaseUrl = 'https://github.enterprise/'
+        String diffUrl = repo.diffUrl(tag1, tag2)
+
+        then:
+        diffUrl == expectedUrl
+
+        where:
+        tag1     | tag2     | expectedUrl
+        "v1.0.0" | "v1.1.0" | "https://github.enterprise/${repo.mnemo}/compare/v1.0.0...v1.1.0"
+        "v1.0.0" | null     | null
+        null     | "v1.1.0" | null
+
+    }
+
     @Unroll
     def "diffUrl for #tag1 and #tag2 is #expectedUrl"() {
         when: