add tests

Author: fatteneder

test/precompile.jl

@@ -1858,6 +1858,38 @@ precompile_test_harness("Issue #50538") do load_path
     @test !isdefined(I50538, :undefglobal)
 end
 
+# check that precompilation workload restores initial state of DEPOT_PATH etc.
+precompile_test_harness("check DEPOT_PATH etc are restored") do load_path
+    write(joinpath(load_path, "modify_depot_path.jl"),
+        """
+        module Modify_DEPOT_PATH
+        empty!(DEPOT_PATH)
+        end
+        """)
+    @test Base.compilecache(Base.PkgId("Modify_DEPOT_PATH")) isa ErrorException
+    write(joinpath(load_path, "modify_load_path.jl"),
+        """
+        module Modify_LOAD_PATH
+        empty!(LOAD_PATH)
+        end
+        """)
+    @test Base.compilecache(Base.PkgId("Modify_LOAD_PATH")) isa ErrorException
+    write(joinpath(load_path, "modify_env.jl"),
+        """
+        module Modify_ENV
+        ENV["modify_ENV"] = true
+        end
+        """)
+    @test Base.compilecache(Base.PkgId("Modify_ENV")) isa ErrorException
+    write(joinpath(load_path, "modify_active_project.jl"),
+        """
+        module Modify_active_project
+        Base.set_active_project!(mktempdir())
+        end
+        """)
+    @test Base.compilecache(Base.PkgId("Modify_active_project")) isa ErrorException
+end
+
 empty!(Base.DEPOT_PATH)
 append!(Base.DEPOT_PATH, original_depot_path)
 empty!(Base.LOAD_PATH)