add test

test/loading.jl

@@ -1331,3 +1331,45 @@ end
         @test filesize(cache_path) != cache_size
     end
 end
+
+@testset "code coverage disabled during precompilation" begin
+    cov_test_dir = joinpath(@__DIR__, "project", "deps", "CovTest.jl")
+    function rm_cov_files()
+        for cov_file in filter(endswith(".cov"), readdir(joinpath(cov_test_dir, "src"), join=true))
+            rm(cov_file)
+        end
+        @test !cov_exists()
+    end
+    cov_exists() = !isempty(filter(endswith(".cov"), readdir(joinpath(cov_test_dir, "src"))))
+
+    mktempdir() do depot
+        rm_cov_files() # clear out any coverage files first
+        @test !cov_exists()
+
+        cd(cov_test_dir) do
+            # In our depot, precompile CovTest.jl with coverage on
+            @test success(addenv(
+                `$(Base.julia_cmd()) --startup-file=no --code-coverage=@ --project -e 'using CovTest; exit(0)'`,
+                "JULIA_DEPOT_PATH" => depot,
+            ))
+            @test !cov_exists()
+            rm_cov_files()
+
+            # same again but call foo(), which is in the pkgimage, and should generate coverage
+            @test success(addenv(
+                `$(Base.julia_cmd()) --startup-file=no --code-coverage=@ --project -e 'using CovTest; foo(); exit(0)'`,
+                "JULIA_DEPOT_PATH" => depot,
+            ))
+            @test cov_exists()
+            rm_cov_files()
+
+            # same again but call bar(), which is NOT in the pkgimage, and should generate coverage
+            @test success(addenv(
+                `$(Base.julia_cmd()) --startup-file=no --code-coverage=@ --project -e 'using CovTest; bar(); exit(0)'`,
+                "JULIA_DEPOT_PATH" => depot,
+            ))
+            @test cov_exists()
+            rm_cov_files()
+        end
+    end
+end

test/project/deps/CovTest.jl/Project.toml

@@ -0,0 +1,3 @@
+name = "CovTest"
+uuid = "f1f4390d-b815-473a-b5dd-5af6e1d717cb"
+version = "0.1.0"

test/project/deps/CovTest.jl/src/CovTest.jl

@@ -0,0 +1,26 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+module CovTest
+
+function foo()
+    x = 1
+    y = 2
+    z = x * y
+    return z
+end
+
+function bar()
+    x = 1
+    y = 2
+    z = x * y
+    return z
+end
+
+if Base.generating_output()
+    # precompile foo but not bar
+    foo()
+end
+
+export foo, bar
+
+end #module