Add create plain reference functionality (#29)

Co-authored-by: marthast <marthast@spotify.com>

Author: Lirick

src/main/java/com/spotify/github/v3/clients/GitDataClient.java

@@ -126,30 +126,38 @@ public CompletableFuture<List<Reference>> listMatchingReferences(final String re
   }
 
   /**
-   * Create a git branch reference. It must not include the refs/heads.
+   * Create a git reference.
    *
-   * @param branch tag name
+   * @param ref reference name
    * @param sha commit to branch from
    */
-  public CompletableFuture<Reference> createBranchReference(final String branch, final String sha) {
+  public CompletableFuture<Reference> createReference(final String ref, final String sha) {
     final String path = format(CREATE_REFERENCE_URI, owner, repo);
     final ImmutableMap<String, String> body = of(
-        "ref", format("refs/heads/%s", branch),
+        "ref", ref,
         "sha", sha
     );
     return github.post(path, github.json().toJsonUnchecked(body), Reference.class);
   }
 
+  /**
+   * Create a git branch reference. It must not include the refs/heads.
+   *
+   * @param branch tag name
+   * @param sha commit to branch from
+   */
+  public CompletableFuture<Reference> createBranchReference(final String branch, final String sha) {
+    return createReference(format("refs/heads/%s", branch), sha);
+  }
+
   /**
    * Create a git tag reference. It must not include the refs/tags.
    *
    * @param tag tag name
    * @param sha commit to tag
    */
   public CompletableFuture<Reference> createTagReference(final String tag, final String sha) {
-    final String path = format(CREATE_REFERENCE_URI, owner, repo);
-    final ImmutableMap<String, String> body = of("ref", format("refs/tags/%s", tag), "sha", sha);
-    return github.post(path, github.json().toJsonUnchecked(body), Reference.class);
+    return createReference(format("refs/tags/%s", tag), sha);
   }
 
   /**

src/test/java/com/spotify/github/v3/clients/GitDataClientTest.java

@@ -102,6 +102,23 @@ public void listMatchingReferences() throws Exception {
   }
 
 
+  public void createReference() throws Exception {
+    final CompletableFuture<Reference> fixture =
+        completedFuture(json.fromJson(getFixture("reference.json"), Reference.class));
+    final ImmutableMap<String, String> body = of(
+        "ref", "featureA",
+        "sha", "aa218f56b14c9653891f9e74264a383fa43fefbd"
+    );
+    when(github.post("/repos/someowner/somerepo/git/refs",
+        github.json().toJsonUnchecked(body),
+        Reference.class))
+        .thenReturn(fixture);
+    final Reference reference =
+        gitDataClient.createReference("featureA", "aa218f56b14c9653891f9e74264a383fa43fefbd").get();
+    assertThat(reference.ref(), is("featureA"));
+    assertThat(reference.object().sha(), is("aa218f56b14c9653891f9e74264a383fa43fefbd"));
+  }
+
   @Test
   public void createBranchReference() throws Exception {
     final CompletableFuture<Reference> fixture =

src/test/resources/com/spotify/github/v3/clients/reference.json

@@ -0,0 +1,10 @@
+{
+  "ref": "featureA",
+  "node_id": "MDM6UmVmcmVmcy9oZWFkcy9mZWF0dXJlQQ==",
+  "url": "https://api.github.com/repos/octocat/Hello-World/git/featureA",
+  "object": {
+    "type": "commit",
+    "sha": "aa218f56b14c9653891f9e74264a383fa43fefbd",
+    "url": "https://api.github.com/repos/octocat/Hello-World/git/commits/aa218f56b14c9653891f9e74264a383fa43fefbd"
+  }
+}