Allow paths for test(; coverage = ...). (#3178)

Fixes #3177.

Co-authored-by: Kristoffer Carlsson <kcarlsson89@gmail.com>

src/Operations.jl

@@ -1526,9 +1526,16 @@ function gen_test_code(source_path::String;
         append!(empty!(ARGS), $(repr(test_args.exec)))
         include($(repr(test_file)))
         """
+    coverage_arg = if coverage isa Bool
+        coverage ? string("@", source_path) : "none"
+    elseif coverage isa AbstractString
+        coverage
+    else
+        throw(ArgumentError("coverage should be a boolean or a string."))
+    end
     return ```
         $(Base.julia_cmd())
-        --code-coverage=$(coverage ? string("@", source_path) : "none")
+        --code-coverage=$(coverage_arg)
         --color=$(Base.have_color === nothing ? "auto" : Base.have_color ? "yes" : "no")
         --compiled-modules=$(Bool(Base.JLOptions().use_compiled_modules) ? "yes" : "no")
         --check-bounds=yes

test/pkg.jl

@@ -240,6 +240,16 @@ temp_pkg_dir() do project_path
         Pkg.rm(TEST_PKG.name)
     end
 
+    @testset "coverage specific path" begin
+        mktempdir() do tmp
+            coverage_path = joinpath(tmp, "tracefile.info")
+            Pkg.add(TEST_PKG.name)
+            Pkg.test(TEST_PKG.name; coverage = coverage_path)
+            @test isfile(coverage_path)
+        end
+        Pkg.rm(TEST_PKG.name)
+    end
+
     @testset "pinning / freeing" begin
         Pkg.add(TEST_PKG.name)
         old_v = Pkg.dependencies()[TEST_PKG.uuid].version