Pull request author placeholder

README.md

@@ -161,6 +161,7 @@ The following placeholders are available and are replaced with:
 Placeholder | Replaced with
 ------------|------------
 `issue_refs` | GitHub issue references to all issues mentioned in the original pull request description seperated by a space, e.g. `#123 #456 zeebe-io/backport-action#789`
+`pull_author` | The username of the original pull request's author, e.g. `korthout`
 `pull_number` | The number of the original pull request that is backported, e.g. `123`
 `target_branch`| The branchname to which the pull request is backported, e.g. `release-0.23`
 

src/backport.ts

@@ -1,7 +1,11 @@
 import * as core from "@actions/core";
 import dedent from "dedent";
 
-import { CreatePullRequestResponse, RequestReviewersResponse } from "./github";
+import {
+  CreatePullRequestResponse,
+  RequestReviewersResponse,
+  PullRequest,
+} from "./github";
 import { GithubApi } from "./github";
 import * as exec from "./exec";
 import * as utils from "./utils";
@@ -134,12 +138,7 @@ export class Backport {
           }
 
           console.info(`Create PR for ${branchname}`);
-          const { title, body } = this.composePRContent(
-            target,
-            mainpr.title,
-            pull_number,
-            mainpr.body
-          );
+          const { title, body } = this.composePRContent(target, mainpr);
           const new_pr_response = await this.github.createPR({
             owner,
             repo,
@@ -208,18 +207,9 @@ export class Backport {
     }
   }
 
-  private composePRContent(
-    target: string,
-    issue_title: string,
-    issue_number: number,
-    original_body: string
-  ): PRContent {
-    const title = `[Backport ${target}] ${issue_title}`;
-    const issues = utils.getMentionedIssueRefs(original_body);
-    const body = this.config.pull.description
-      .replace("${pull_number}", issue_number.toString())
-      .replace("${target_branch}", target)
-      .replace("${issue_refs}", issues.join(" "));
+  private composePRContent(target: string, main: PullRequest): PRContent {
+    const title = `[Backport ${target}] ${main.title}`;
+    const body = utils.composeBody(this.config.pull.description, main, target);
     return { title, body };
   }
 

src/github.ts

@@ -94,6 +94,9 @@ export type PullRequest = {
   base: {
     sha: string;
   };
+  user: {
+    login: string;
+  };
   labels: {
     name: string;
   }[];

src/test/utils.test.ts

@@ -1,5 +1,5 @@
 import dedent from "dedent";
-import { getMentionedIssueRefs } from "../utils";
+import { getMentionedIssueRefs, composeBody } from "../utils";
 
 describe("get mentioned issues", () => {
   describe("returns an empty list", () => {
@@ -128,8 +128,95 @@ describe("get mentioned issues", () => {
       ]);
     });
   });
+});
+
+describe("compose body", () => {
+  const main_default = {
+    number: 123,
+    body: "foo-body",
+    user: { login: "foo-author" },
+  };
+  const target = "foo-target";
+
+  describe("returns same value as provided template", () => {
+    it("for an empty template", () => {
+      expect(composeBody("", main_default, target)).toEqual("");
+    });
+
+    it("for a template without placeholders", () => {
+      const template = text({});
+      expect(composeBody(template, main_default, target)).toEqual(template);
+    });
+
+    it("for a template with unknown placeholders", () => {
+      const template = text({
+        start: "${abc}",
+        middle: "${def}",
+        end: "${ghi}",
+        part: "${jkl}",
+      });
+      expect(composeBody(template, main_default, target)).toEqual(template);
+    });
+  });
+
+  describe("returns evaluated templated", () => {
+    it("for a template with target_branch placeholder", () => {
+      const template = "Backport of some-title to `${target_branch}`";
+      expect(composeBody(template, main_default, target)).toEqual(
+        "Backport of some-title to `foo-target`"
+      );
+    });
+
+    it("for a template with pull_number placeholder", () => {
+      const template = "Backport of #${pull_number} to some-target";
+      expect(composeBody(template, main_default, target)).toEqual(
+        "Backport of #123 to some-target"
+      );
+    });
+
+    describe("for a template with issue_refs placeholder", () => {
+      const template = "Backport that refers to: ${issue_refs}";
+
+      it("and body has no referred issues", () => {
+        expect(composeBody(template, main_default, target)).toEqual(
+          "Backport that refers to: "
+        );
+      });
 
-  // todo deal with urls to unrelated repos
+      it("and body has a referred issue", () => {
+        expect(
+          composeBody(
+            template,
+            {
+              ...main_default,
+              body: "Body mentions #123 and that's it.",
+            },
+            target
+          )
+        ).toEqual("Backport that refers to: #123");
+      });
+
+      it("and body has some referred issues", () => {
+        expect(
+          composeBody(
+            template,
+            {
+              ...main_default,
+              body: "This body refers to #123 and foo/bar#456",
+            },
+            target
+          )
+        ).toEqual("Backport that refers to: #123 foo/bar#456");
+      });
+    });
+
+    it("for a template with pull_author placeholder", () => {
+      const template = "Backport of pull made by @${pull_author}";
+      expect(composeBody(template, main_default, target)).toEqual(
+        "Backport of pull made by @foo-author"
+      );
+    });
+  });
 });
 
 function text({

src/utils.ts

@@ -1,3 +1,41 @@
+/**
+ * @param template The backport description template
+ * @param main The main pull request that is backported
+ * @param target The target branchname
+ * @returns Description that can be used as the backport pull request body
+ */
+export function composeBody(
+  template: string,
+  main: PullRequest,
+  target: string
+): string {
+  const issues = getMentionedIssueRefs(main.body);
+  return template
+    .replace("${pull_author}", main.user.login)
+    .replace("${pull_number}", main.number.toString())
+    .replace("${target_branch}", target)
+    .replace("${issue_refs}", issues.join(" "));
+}
+
+type PullRequest = {
+  number: number;
+  body: string;
+  user: {
+    login: string;
+  };
+};
+
+/**
+ * @param body Text in which to search for mentioned issues
+ * @returns All found mentioned issues as GitHub issue references
+ */
+export function getMentionedIssueRefs(body: string): string[] {
+  const issueUrls =
+    body.match(patterns.url.global)?.map((url) => toRef(url)) ?? [];
+  const issueRefs = body.match(patterns.ref) ?? [];
+  return issueUrls.concat(issueRefs).map((ref) => ref.trim());
+}
+
 const patterns = {
   // matches urls to github issues at start, middle, end of line as individual word
   // may be lead and trailed by whitespace which should be trimmed
@@ -17,17 +55,6 @@ const patterns = {
   ref: /(?:^| )((?<org>[^\n #\/]+)\/(?<repo>[^\n #\/]+))?#(?<number>[0-9]+)(?: |$)/gm,
 };
 
-/**
- * @param body Text in which to search for mentioned issues
- * @returns All found mentioned issues as GitHub issue references
- */
-export function getMentionedIssueRefs(body: string): string[] {
-  const issueUrls =
-    body.match(patterns.url.global)?.map((url) => toRef(url)) ?? [];
-  const issueRefs = body.match(patterns.ref) ?? [];
-  return issueUrls.concat(issueRefs).map((ref) => ref.trim());
-}
-
 const toRef = (url: string) => {
   // matchAll is not yet available to directly access the captured groups of all matches
   // so this maps the urls to GitHub refs by matching again without the global flag