Correctly handle an edge case in the sequential version check (#563)

* Add the `ErrorCannotComputeVersionDifference` struct

* Allow `difference(x, y)` to return an `ErrorCannotComputeVersionDifference` (instead of throwing an exception)

* Add a message field to `ErrorCannotComputeVersionDifference`

* `_valid_change()`: correctly handle `ErrorCannotComputeVersionDifference`

* Patch bump: bump from 10.3.0 to 10.3.1

* Fix two unit tests

Project.toml

@@ -1,7 +1,7 @@
 name = "RegistryCI"
 uuid = "0c95cc5f-2f7e-43fe-82dd-79dbcba86b32"
 authors = ["Dilum Aluthge <dilum@aluthge.com>", "Fredrik Ekre <ekrefredrik@gmail.com>", "contributors"]
-version = "10.3.0"
+version = "10.3.1"
 
 [deps]
 Base64 = "2a0f44e3-6c83-55bd-87e4-b1978d98bd5f"

src/AutoMerge/guidelines.jl

@@ -501,6 +501,16 @@ end
 
 function _valid_change(old_version::VersionNumber, new_version::VersionNumber)
     diff = difference(old_version, new_version)
+    if !(diff isa VersionNumber)
+        if diff isa ErrorCannotComputeVersionDifference
+            old_msg = diff.msg
+        else
+            T = typeof(diff)
+            old_msg = "Unknown diff type: $(T)"
+        end
+        new_msg = "Error occured while trying to compute version bump. Message: $(old_msg)"
+        return _invalid_sequential_version(new_msg)
+    end
     @debug("Difference between versions: ", old_version, new_version, diff)
     if diff == v"0.0.1"
         return true, "", :patch

src/AutoMerge/semver.jl

@@ -14,9 +14,9 @@ function difference(x::VersionNumber, y::VersionNumber)
     elseif y.patch > x.patch
         return VersionNumber(y.major - x.major, y.minor - x.minor, y.patch - x.patch)
     else
-        throw(
-            ArgumentError("first argument must be strictly less than the second argument")
-        )
+        msg = "first argument $(x) must be strictly less than the second argument $(y)"
+        @warn msg x y
+        return ErrorCannotComputeVersionDifference(msg)
     end
 end
 

src/AutoMerge/types.jl

@@ -35,6 +35,10 @@ struct AutoMergeWrongBuildType <: AutoMergeException
     msg::String
 end
 
+struct ErrorCannotComputeVersionDifference
+    msg::String
+end
+
 struct GitHubAutoMergeData
     # Handle to the GitHub API. Used to query the PR and update
     # comments and status.

test/automerge-unit.jl

@@ -527,8 +527,8 @@ end
         @test AutoMerge.nextmajor(v"1.2") == v"2"
         @test AutoMerge.nextmajor(v"1.2.3") == v"2"
         @test AutoMerge.difference(v"1", v"2") == v"1"
-        @test_throws ArgumentError AutoMerge.difference(v"1", v"1")
-        @test_throws ArgumentError AutoMerge.difference(v"2", v"1")
+        @test AutoMerge.difference(v"1", v"1") isa AutoMerge.ErrorCannotComputeVersionDifference
+        @test AutoMerge.difference(v"2", v"1") isa AutoMerge.ErrorCannotComputeVersionDifference
         @test !AutoMerge._has_upper_bound(Pkg.Types.VersionRange("0"))
         @test AutoMerge._has_upper_bound(Pkg.Types.VersionRange("1"))
         @test !AutoMerge._has_upper_bound(Pkg.Types.VersionRange("*"))