Make relpath_from_repo_root, repo_commit throw when file doesn't exists (#1923)

Author: clouds56

src/Utilities/Utilities.jl

@@ -420,13 +420,15 @@ Returns the path of `file`, relative to the root of the Git repository, or `noth
 file is not in a Git repository.
 """
 function relpath_from_repo_root(file)
+    isfile(file) || error("relpath_from_repo_root called with nonexistent file: $file")
     cd(dirname(file)) do
         root = repo_root(file)
         root !== nothing && startswith(file, root) ? relpath(file, root) : nothing
     end
 end
 
 function repo_commit(file)
+    isfile(file) || error("repo_commit called with nonexistent file: $file")
     cd(dirname(file)) do
         readchomp(`$(git()) rev-parse HEAD`)
     end

test/utilities.jl

@@ -192,7 +192,7 @@ end
             @test Documenter.Utilities.relpath_from_repo_root(filepath) == joinpath("src", "SourceFile.jl")
             # We assume that a temporary file is not in a repo
             @test Documenter.Utilities.repo_root(tempname()) == nothing
-            @test Documenter.Utilities.relpath_from_repo_root(tempname()) == nothing
+            @test_throws ErrorException Documenter.Utilities.relpath_from_repo_root(tempname())
         end
 
         # Test worktree
@@ -214,7 +214,7 @@ end
             @test Documenter.Utilities.relpath_from_repo_root(filepath) == joinpath("src", "SourceFile.jl")
             # We assume that a temporary file is not in a repo
             @test Documenter.Utilities.repo_root(tempname()) == nothing
-            @test Documenter.Utilities.relpath_from_repo_root(tempname()) == nothing
+            @test_throws ErrorException Documenter.Utilities.relpath_from_repo_root(tempname())
         end
 
         # Test submodule
@@ -249,7 +249,7 @@ end
             @test Documenter.Utilities.relpath_from_repo_root(filepath) == joinpath("src", "SourceFile.jl")
             # We assume that a temporary file is not in a repo
             @test Documenter.Utilities.repo_root(tempname()) == nothing
-            @test Documenter.Utilities.relpath_from_repo_root(tempname()) == nothing
+            @test_throws ErrorException Documenter.Utilities.relpath_from_repo_root(tempname())
         end
 
         # This tests the case where the origin.url is some unrecognised Git hosting service, in which case we are unable