From bf068577a738c80ccf33d4b62e6237414d7158bc Mon Sep 17 00:00:00 2001
From: Benny Wong <benny@bwong.net>
Date: Thu, 7 Sep 2017 22:55:28 -0400
Subject: [PATCH] GitDSL: Include created and removed files for
 `JSONDiffForFile`

* Related to: danger/danger-js#368
---
 changelog.md                                  |  2 +-
 source/platforms/github/GitHubGit.ts          | 30 ++++++++----
 .../github/_tests/_github_git.test.ts         | 48 +++++++++++++++++++
 3 files changed, 70 insertions(+), 10 deletions(-)

diff --git a/changelog.md b/changelog.md
index b87c73683..5352ed708 100644
--- a/changelog.md
+++ b/changelog.md
@@ -2,7 +2,7 @@
 
 ### Master
 
-- Updates `diffForFile` and `JSONPatchForFile` to include created and removed files - #368 - bdotdub
+- Updates `diffForFile`, `JSONPatchForFile`, and `JSONDiffForFile` to include created and removed files - #368 - bdotdub
 
 ### 2.0.0-alpha.14
 
diff --git a/source/platforms/github/GitHubGit.ts b/source/platforms/github/GitHubGit.ts
index fdf4bf274..420a823ec 100644
--- a/source/platforms/github/GitHubGit.ts
+++ b/source/platforms/github/GitHubGit.ts
@@ -106,25 +106,37 @@ export default async function gitDSLForGitHub(api: GitHubAPI): Promise<GitDSL> {
       const backAStepPath = pathSteps.length <= 2 ? path : pathSteps.slice(0, pathSteps.length - 1).join("/")
 
       const diff: any = {
-        after: jsonpointer.get(after, backAStepPath),
-        before: jsonpointer.get(before, backAStepPath),
+        after: jsonpointer.get(after, backAStepPath) || null,
+        before: jsonpointer.get(before, backAStepPath) || null,
       }
 
+      const counterpart = (other) => {
+        if (Array.isArray(other)) {
+          return []
+        } else if (isobject(diff.after)) {
+          return {}
+        }
+
+        return null
+      }
+
+      const beforeValue = diff.before || counterpart(diff.after)
+      const afterValue = diff.after || counterpart(diff.before)
+
       // If they both are arrays, add some extra metadata about what was
       // added or removed. This makes it really easy to act on specific
       // changes to JSON DSLs
 
-      if (Array.isArray(diff.after) && Array.isArray(diff.before)) {
-        const arrayBefore = diff.before as any[]
-        const arrayAfter = diff.after as any[]
+      if (Array.isArray(afterValue) && Array.isArray(beforeValue)) {
+        const arrayBefore = beforeValue as any[]
+        const arrayAfter = afterValue as any[]
 
         diff.added = arrayAfter.filter(o => !includes(arrayBefore, o))
         diff.removed = arrayBefore.filter(o => !includes(arrayAfter, o))
-
         // Do the same, but for keys inside an object if they both are objects.
-      } else if (isobject(diff.after) && isobject(diff.before)) {
-        const beforeKeys = keys(diff.before) as string[]
-        const afterKeys = keys(diff.after) as string[]
+      } else if (isobject(afterValue) && isobject(beforeValue)) {
+        const beforeKeys = keys(beforeValue) as string[]
+        const afterKeys = keys(afterValue) as string[]
         diff.added = afterKeys.filter(o => !includes(beforeKeys, o))
         diff.removed = beforeKeys.filter(o => !includes(afterKeys, o))
       }
diff --git a/source/platforms/github/_tests/_github_git.test.ts b/source/platforms/github/_tests/_github_git.test.ts
index e9e1e3961..21ad4a734 100644
--- a/source/platforms/github/_tests/_github_git.test.ts
+++ b/source/platforms/github/_tests/_github_git.test.ts
@@ -235,6 +235,54 @@ describe("the dangerfile gitDSL", async () => {
       expect(empty).toEqual({})
     })
 
+    it("handles showing a patch for a created file", async () => {
+      github.api.fileContents = async (path, repo, ref) => {
+        const after = {
+          a: "o, world",
+          b: 3,
+          c: ["one", "two", "three", "four"],
+          d: ["one", "two"],
+          e: ["five", "one", "three"],
+        }
+
+        const obj = ref === masterSHA ? {} : after
+        return JSON.stringify(obj)
+      }
+      const gitDSL = await github.getPlatformGitRepresentation()
+      const empty = await gitDSL.JSONDiffForFile("data/schema.json")
+      expect(empty).toEqual({
+        a: { after: "o, world", before: null },
+        b: { after: 3, before: null },
+        c: { added: ["one", "two", "three", "four"], after: ["one", "two", "three", "four"], before: null, removed: [] },
+        d: { added: ["one", "two"], after: ["one", "two"], before: null, removed: [] },
+        e: { added: ["five", "one", "three"], after: ["five", "one", "three"], before: null, removed: [] },
+      })
+    })
+
+    it("handles showing a patch for a deleted file", async () => {
+      github.api.fileContents = async (path, repo, ref) => {
+        const before = {
+          a: "o, world",
+          b: 3,
+          c: ["one", "two", "three", "four"],
+          d: ["one", "two"],
+          e: ["five", "one", "three"],
+        }
+
+        const obj = ref === masterSHA ? before : {}
+        return JSON.stringify(obj)
+      }
+      const gitDSL = await github.getPlatformGitRepresentation()
+      const empty = await gitDSL.JSONDiffForFile("data/schema.json")
+      expect(empty).toEqual({
+        a: { after: null, before: "o, world" },
+        b: { after: null, before: 3 },
+        c: { added: [], after: null, before: ["one", "two", "three", "four"], removed: ["one", "two", "three", "four"] },
+        d: { added: [], after: null, before: ["one", "two",], removed: ["one", "two"] },
+        e: { added: [], after: null, before: ["five", "one", "three"], removed: ["five", "one", "three"] },
+      })
+    })
+
     it("handles showing a patch for two different diff files", async () => {
       github.api.fileContents = async (path, repo, ref) => {
         const before = {