Include Pull additions/deletions (#444)

This adds additions and deletions to the v3 Pull data model, and also
uses them in the pull descriptions.

It's basically a port of #340 to v3.

Test plan: Snapshots

src/v3/plugins/github/__snapshots__/relationalView.test.js.snap

@@ -71,6 +71,8 @@ Array [
 ]
 `;
 
+exports[`plugins/github/relationalView Pull has additions 1`] = `1`;
+
 exports[`plugins/github/relationalView Pull has body 1`] = `
 "@wchargin could you please do the following:
 - add a commit comment
@@ -79,6 +81,8 @@ exports[`plugins/github/relationalView Pull has body 1`] = `
 - then approve the pr"
 `;
 
+exports[`plugins/github/relationalView Pull has deletions 1`] = `0`;
+
 exports[`plugins/github/relationalView Pull has mergedAs 1`] = `
 Object {
   "hash": "6d5b3aa31ebb68a06ceb46bbd6cf49b6ccd6f5e6",

src/v3/plugins/github/__snapshots__/render.test.js.snap

@@ -2,11 +2,11 @@
 
 exports[`plugins/github/render descriptions are as expected 1`] = `
 Object {
-  "comment": "comment by @wchargin on review by @wchargin of #5: This pull request will be more contentious. I can feel it...",
+  "comment": "comment by @wchargin on review by @wchargin of #5 (+1/−0): This pull request will be more contentious. I can feel it...",
   "issue": "#2: A referencing issue.",
-  "pull": "#5: This pull request will be more contentious. I can feel it...",
+  "pull": "#5 (+1/−0): This pull request will be more contentious. I can feel it...",
   "repo": "sourcecred/example-github",
-  "review": "review by @wchargin of #5: This pull request will be more contentious. I can feel it...",
+  "review": "review by @wchargin of #5 (+1/−0): This pull request will be more contentious. I can feel it...",
   "userlike": "@wchargin",
 }
 `;

src/v3/plugins/github/relationalView.js

@@ -255,6 +255,8 @@ export class RelationalView {
       body: json.body,
       title: json.title,
       mergedAs,
+      additions: json.additions,
+      deletions: json.deletions,
     };
     this._pulls.set(N.toRaw(address), entry);
     return address;
@@ -565,6 +567,8 @@ type PullEntry = {|
   +reviews: ReviewAddress[],
   +mergedAs: ?GitNode.CommitAddress,
   +nominalAuthor: ?UserlikeAddress,
+  +additions: number,
+  +deletions: number,
 |};
 
 export class Pull extends _Entity<PullEntry> {
@@ -585,6 +589,12 @@ export class Pull extends _Entity<PullEntry> {
   body(): string {
     return this._entry.body;
   }
+  additions(): number {
+    return this._entry.additions;
+  }
+  deletions(): number {
+    return this._entry.deletions;
+  }
   mergedAs(): ?GitNode.CommitAddress {
     return this._entry.mergedAs;
   }

src/v3/plugins/github/relationalView.test.js

@@ -106,6 +106,8 @@ describe("plugins/github/relationalView", () => {
     has("url", () => entity.url());
     has("parent", () => entity.parent());
     has("mergedAs", () => entity.mergedAs());
+    has("additions", () => entity.additions());
+    has("deletions", () => entity.deletions());
     hasEntities("reviews", () => entity.reviews());
     hasEntities("comments", () => entity.comments());
     hasEntities("authors", () => entity.authors());

src/v3/plugins/github/render.js

@@ -14,7 +14,10 @@ export function description(e: R.Entity) {
   const handlers = {
     repo: (x) => `${x.owner()}/${x.name()}`,
     issue: (x) => `#${x.number()}: ${x.title()}`,
-    pull: (x) => `#${x.number()}: ${x.title()}`,
+    pull: (x) => {
+      const diff = `+${x.additions()}/\u2212${x.deletions()}`;
+      return `#${x.number()} (${diff}): ${x.title()}`;
+    },
     review: (x) => `review ${withAuthors(x)}of ${description(x.parent())}`,
     comment: (x) => `comment ${withAuthors(x)}on ${description(x.parent())}`,
     userlike: (x) => `@${x.login()}`,