Link to meta.changelog in PR description

We now have the bot:

1. Doing the automated upgrade (bump version, src, recomputing hash)
2. Doing a full nixpkgs-review reverse closure rebuild

The next step for a human is to review the upstream changelog. Right now they
have to find it manually, but if `meta.changelog` is set, this commit adds a
link to it directly in the PR description .

Resolves #44

src/Nix.hs

@@ -10,6 +10,7 @@ module Nix
     build,
     cachix,
     getAttr,
+    getChangelog,
     getDerivationFile,
     getDescription,
     getDrvAttr,
@@ -197,6 +198,16 @@ getIsBroken attrPath =
     & readNixBool
     & overwriteErrorT ("Could not get meta.broken for attrpath " <> attrPath)
 
+getChangelog :: MonadIO m => Text -> ExceptT Text m Text
+getChangelog attrPath =
+  nixEvalET
+    (EvalOptions NoRaw (Env []))
+    ( "(let pkgs = import ./. {}; in pkgs."
+        <> attrPath
+        <> ".meta.changelog or \"\")"
+    )
+    & overwriteErrorT ("Could not get meta.changelog for attrpath " <> attrPath)
+
 getDescription :: MonadIO m => Text -> ExceptT Text m Text
 getDescription attrPath =
   nixEvalET

src/Update.hs

@@ -295,6 +295,7 @@ publishPackage log updateEnv oldSrcUrl newSrcUrl attrPath result opDiff rewriteM
       Left msg -> pure msg
   metaDescription <- Nix.getDescription attrPath <|> return T.empty
   metaHomepage <- Nix.getHomepageET attrPath <|> return T.empty
+  metaChangelog <- Nix.getChangelog attrPath <|> return T.empty
   cveRep <- liftIO $ cveReport updateEnv
   releaseUrl <- GH.releaseUrl updateEnv newSrcUrl <|> return ""
   compareUrl <- GH.compareUrl oldSrcUrl newSrcUrl <|> return ""
@@ -320,6 +321,7 @@ publishPackage log updateEnv oldSrcUrl newSrcUrl attrPath result opDiff rewriteM
           isBroken
           metaDescription
           metaHomepage
+          metaChangelog
           rewriteMsgs
           releaseUrl
           compareUrl
@@ -354,6 +356,7 @@ prMessage ::
   Bool ->
   Text ->
   Text ->
+  Text ->
   [Text] ->
   Text ->
   Text ->
@@ -367,7 +370,7 @@ prMessage ::
   Text ->
   Text ->
   Text
-prMessage updateEnv isBroken metaDescription metaHomepage rewriteMsgs releaseUrl compareUrl resultCheckReport commitHash attrPath maintainers resultPath opReport cveRep cachixTestInstructions nixpkgsReviewMsg =
+prMessage updateEnv isBroken metaDescription metaHomepage metaChangelog rewriteMsgs releaseUrl compareUrl resultCheckReport commitHash attrPath maintainers resultPath opReport cveRep cachixTestInstructions nixpkgsReviewMsg =
   -- Some components of the PR description are pre-generated prior to calling
   -- because they require IO, but in general try to put as much as possible for
   -- the formatting into the pure function so that we can control the body
@@ -376,11 +379,15 @@ prMessage updateEnv isBroken metaDescription metaHomepage rewriteMsgs releaseUrl
       metaHomepageLine =
         if metaHomepage == T.empty
           then ""
-          else "\nmeta.homepage for " <> attrPath <> " is: " <> metaHomepage
+          else "meta.homepage for " <> attrPath <> " is: " <> metaHomepage
       metaDescriptionLine =
         if metaDescription == T.empty
           then ""
-          else "\n\nmeta.description for " <> attrPath <> " is: " <> metaDescription
+          else "meta.description for " <> attrPath <> " is: " <> metaDescription
+      metaChangelogLine =
+        if metaDescription == T.empty
+          then ""
+          else "meta.changelog for " <> attrPath <> " is: " <> metaChangelog
       rewriteMsgsLine = foldl (\ms m -> ms <> T.pack "\n- " <> m) "\n###### Updates performed" rewriteMsgs
       maintainersCc =
         if not (T.null maintainers)
@@ -412,8 +419,13 @@ prMessage updateEnv isBroken metaDescription metaHomepage rewriteMsgs releaseUrl
    in [interpolate|
        Semi-automatic update generated by [nixpkgs-update](https://github.com/ryantm/nixpkgs-update) tools. $sourceLinkInfo
        $brokenMsg
+
        $metaDescriptionLine
+
        $metaHomepageLine
+
+       $metaChangelogLine
+
        $rewriteMsgsLine
 
        ###### To inspect upstream changes

test/UpdateSpec.hs

@@ -23,6 +23,7 @@ spec = do
     let isBroken = False
     let metaDescription = "\"Foobar package description\""
     let metaHomepage = "\"https://foobar-homepage.com\""
+    let metaChangelog = "\"https://foobar-homepage.com/changelog/v1.2.3\""
     let rewriteMsgs = ["Version Update", "Other Update"]
     let releaseUrl = "https://github.com/foobar/releases"
     let compareUrl = "https://github.com/foobar/compare"
@@ -38,13 +39,13 @@ spec = do
 
     it "matches a simple mock example" do
       expected <- T.readFile "test_data/expected_pr_description_1.md"
-      let actual = Update.prMessage updateEnv isBroken metaDescription metaHomepage rewriteMsgs releaseUrl compareUrl resultCheckReport commitHash attrPath maintainersCc resultPath opReport cveRep cachixTestInstructions nixpkgsReviewMsg
+      let actual = Update.prMessage updateEnv isBroken metaDescription metaHomepage metaChangelog rewriteMsgs releaseUrl compareUrl resultCheckReport commitHash attrPath maintainersCc resultPath opReport cveRep cachixTestInstructions nixpkgsReviewMsg
       T.writeFile "test_data/actual_pr_description_1.md" actual
       actual `shouldBe` expected
 
     it "does not include NixPkgs review section when no review was done" do
       expected <- T.readFile "test_data/expected_pr_description_2.md"
       let nixpkgsReviewMsg' = ""
-      let actual = Update.prMessage updateEnv isBroken metaDescription metaHomepage rewriteMsgs releaseUrl compareUrl resultCheckReport commitHash attrPath maintainersCc resultPath opReport cveRep cachixTestInstructions nixpkgsReviewMsg'
+      let actual = Update.prMessage updateEnv isBroken metaDescription metaHomepage metaChangelog rewriteMsgs releaseUrl compareUrl resultCheckReport commitHash attrPath maintainersCc resultPath opReport cveRep cachixTestInstructions nixpkgsReviewMsg'
       T.writeFile "test_data/actual_pr_description_2.md" actual
       actual `shouldBe` expected

test_data/expected_pr_description_1.md

@@ -1,11 +1,13 @@
 Semi-automatic update generated by [nixpkgs-update](https://github.com/ryantm/nixpkgs-update) tools. This update was made based on information from https://update-site.com.
 
 
-
 meta.description for foobar is: "Foobar package description"
 
 meta.homepage for foobar is: "https://foobar-homepage.com"
 
+meta.changelog for foobar is: "https://foobar-homepage.com/changelog/v1.2.3"
+
+
 ###### Updates performed
 - Version Update
 - Other Update

test_data/expected_pr_description_2.md

@@ -1,11 +1,13 @@
 Semi-automatic update generated by [nixpkgs-update](https://github.com/ryantm/nixpkgs-update) tools. This update was made based on information from https://update-site.com.
 
 
-
 meta.description for foobar is: "Foobar package description"
 
 meta.homepage for foobar is: "https://foobar-homepage.com"
 
+meta.changelog for foobar is: "https://foobar-homepage.com/changelog/v1.2.3"
+
+
 ###### Updates performed
 - Version Update
 - Other Update