diff --git a/.github/workflows/Test.yml b/.github/workflows/Test.yml
index 00fff31..ef773d2 100644
--- a/.github/workflows/Test.yml
+++ b/.github/workflows/Test.yml
@@ -35,6 +35,8 @@ jobs:
       - uses: julia-actions/cache@v2
       - uses: julia-actions/julia-runtest@v1
       - uses: julia-actions/julia-processcoverage@v1
+        with:
+          directories: "src,juliac"
       - uses: codecov/codecov-action@v4
         with:
           file: lcov.info
diff --git a/test/maintests.jl b/test/maintests.jl
new file mode 100644
index 0000000..d308a84
--- /dev/null
+++ b/test/maintests.jl
@@ -0,0 +1,366 @@
+# SPDX-License-Identifier: MIT
+
+using Test: @test
+using Runic: Runic
+
+function maintests(f::R) where {R}
+
+    bad = "1+1"
+    good = "1 + 1\n"
+
+    # Utils
+    function cdtmp(f)
+        return mktempdir(tmp -> cd(f, tmp))
+    end
+    function runic(std_in::String)
+        return runic(String[], std_in)
+    end
+    function runic(argv::Vector{String} = String[], std_in::String = "")
+        rc, stdout_str, stderr_str = mktemp() do stdin_path, stdin
+            write(stdin_path, std_in)
+            mktemp() do stdout_path, stdout
+                mktemp() do stderr_path, stderr
+                    rc = redirect_stdio(() -> f(copy(argv)); stdin, stdout, stderr)
+                    close(stderr)
+                    close(stdout)
+                    return rc, read(stdout_path, String), read(stderr_path, String)
+                end
+            end
+        end
+        return rc, stdout_str, stderr_str
+    end
+
+    # runic --help
+    let (rc, fd1, fd2) = runic(["--help"])
+        @test rc == 0
+        @test occursin("Runic.main - format Julia source code", fd1)
+        @test isempty(fd2)
+    end
+
+    # runic --version
+    let (rc, fd1, fd2) = runic(["--version"])
+        @test rc == 0
+        @test occursin("runic version $(Runic.RUNIC_VERSION), julia version $(VERSION)", fd1)
+        @test isempty(fd2)
+    end
+
+    # runic <stdin >stdout
+    for argv in [
+            String[], ["-"],
+            ["--output=-"], ["-o", "-"],
+            ["--output=-", "-"], ["-o", "-", "-"],
+        ]
+        rc, fd1, fd2 = runic(argv, bad)
+        @test rc == 0
+        @test occursin(good, fd1)
+        @test isempty(fd2)
+    end
+
+    # runic --output=out.jl <stdin
+    cdtmp() do
+        f_out = "out.jl"
+        for argv in [
+                ["--output=$f_out"], ["-o", f_out],
+                ["--output=$f_out", "-"], ["-o", f_out, "-"],
+            ]
+            rm(f_out, force = true)
+            rc, fd1, fd2 = runic(argv, bad)
+            @test rc == 0
+            @test isempty(fd1)
+            @test isempty(fd2)
+            @test read(f_out, String) == good
+        end
+    end
+
+    # runic in.jl >stdout
+    cdtmp() do
+        f_in = "in.jl"
+        write(f_in, bad)
+        for argv in [[f_in], ["--output=-", f_in], ["-o", "-", f_in]]
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 0
+            @test occursin(good, fd1)
+            @test isempty(fd2)
+            @test read(f_in, String) == bad
+        end
+    end
+
+    # runic --output=out.jl in.jl
+    cdtmp() do
+        f_in = "in.jl"
+        write(f_in, bad)
+        f_out = "out.jl"
+        for argv in [["--output=$f_out", f_in], ["-o", f_out, f_in]]
+            rm(f_out, force = true)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 0
+            @test isempty(fd1)
+            @test occursin("Formatting `in.jl` -> `out.jl` ...", fd2)
+            @test occursin("✔", fd2)
+            @test !occursin("✖", fd2)
+            @test read(f_out, String) == good
+            @test read(f_in, String) == bad
+        end
+    end
+
+    # runic --inplace in.jl (bad input)
+    cdtmp() do
+        f_in = "in.jl"
+        for argv in [["--inplace", f_in], ["-i", f_in]]
+            write(f_in, bad)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 0
+            @test isempty(fd1)
+            @test occursin("Formatting `in.jl` ...", fd2)
+            @test occursin("✔", fd2)
+            @test !occursin("✖", fd2)
+            @test read(f_in, String) == good
+        end
+    end
+
+    # runic --inplace in.jl (good input)
+    cdtmp() do
+        f_in = "in.jl"
+        for argv in [["--inplace", f_in], ["-i", f_in]]
+            write(f_in, good)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 0
+            @test isempty(fd1)
+            @test occursin("Formatting `in.jl` ...", fd2)
+            @test occursin("✔", fd2)
+            @test !occursin("✖", fd2)
+            @test read(f_in, String) == good
+        end
+    end
+
+    # runic --inplace in/
+    cdtmp() do
+        fgood = "good.jl"
+        mkdir("src")
+        fbad = joinpath("src", "bad.jl")
+        mkdir(".git")
+        gitfile = joinpath(".git", "git.jl")
+        write(gitfile, "this is not a Julia file")
+        markdownfile = "markdown.md"
+        write(markdownfile, "this is not a Julia file")
+        for argv in [["--inplace", "."], ["-i", "."], ["-i", ".", "src"]]
+            write(fgood, good)
+            write(fbad, bad)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 0
+            @test isempty(fd1)
+            @test occursin("Formatting `good.jl` ...", fd2)
+            @test occursin("Formatting `src/bad.jl` ...", fd2)
+            @test occursin("✔", fd2)
+            @test !occursin("✖", fd2)
+            @test !occursin("git.jl", fd2)
+            @test !occursin("markdown.jl", fd2)
+            @test read(fgood, String) == read(fbad, String) == good
+        end
+    end
+
+    # runic --check in.jl (bad input)
+    cdtmp() do
+        f_in = "in.jl"
+        for argv in [["--check", f_in], ["-c", f_in]]
+            write(f_in, bad)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 1
+            @test isempty(fd1)
+            @test occursin("Checking `in.jl` ...", fd2)
+            @test !occursin("✔", fd2)
+            @test occursin("✖", fd2)
+            @test read(f_in, String) == bad
+        end
+    end
+
+    # runic --check in.jl (good input)
+    cdtmp() do
+        f_in = "in.jl"
+        for argv in [["--check", f_in], ["-c", f_in]]
+            write(f_in, good)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 0
+            @test isempty(fd1)
+            @test occursin("Checking `in.jl` ...", fd2)
+            @test occursin("✔", fd2)
+            @test !occursin("✖", fd2)
+            @test read(f_in, String) == good
+        end
+    end
+
+    # runic --check in/
+    cdtmp() do
+        fgood = "good.jl"
+        mkdir("src")
+        fbad = joinpath("src", "bad.jl")
+        mkdir(".git")
+        gitfile = joinpath(".git", "git.jl")
+        write(gitfile, "this is not a Julia file")
+        markdownfile = "markdown.md"
+        write(markdownfile, "this is not a Julia file")
+        for argv in [["--check", "."], ["-c", "."]]
+            write(fgood, good)
+            write(fbad, bad)
+            rc, fd1, fd2 = runic(argv)
+            @test rc == 1
+            @test isempty(fd1)
+            @test occursin("Checking `good.jl` ...", fd2)
+            @test occursin("Checking `src/bad.jl` ...", fd2)
+            @test occursin("✔", fd2)
+            @test occursin("✖", fd2)
+            @test !occursin("git.jl", fd2)
+            @test !occursin("markdown.jl", fd2)
+            @test read(fgood, String) == good
+            @test read(fbad, String) == bad
+        end
+    end
+
+    # runic --check --diff in.jl
+    if Sys.which("git") !== nothing
+        cdtmp() do
+            f_in = "in.jl"
+            for argv in [["--check", "--diff", f_in], ["-c", "-d", f_in]]
+                write(f_in, bad)
+                rc, fd1, fd2 = runic(argv)
+                @test rc == 1
+                @test isempty(fd1)
+                @test occursin("Checking `in.jl` ...", fd2)
+                @test !occursin("✔", fd2)
+                @test occursin("✖", fd2)
+                @test occursin("diff --git", fd2)
+                @test occursin("-1+1", fd2)
+                @test occursin("+1 + 1", fd2)
+                @test read(f_in, String) == bad
+            end
+        end
+    end
+
+    # Error paths
+    # runic -o
+    let (rc, fd1, fd2) = runic(["-o"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("expected output file argument after `-o`", fd2)
+    end
+
+    # runic in.jl -
+    let (rc, fd1, fd2) = runic(["in.jl", "-"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("input `-` can not be used with multiple files", fd2)
+    end
+
+    # runic --inplace --check (TODO: perhaps this should be allowed?)
+    let (rc, fd1, fd2) = runic(["--inplace", "--check"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("options `--inplace` and `--check` are mutually exclusive", fd2)
+    end
+
+    # runic --inplace --output=out.jl in.jl
+    let (rc, fd1, fd2) = runic(["--inplace", "--output=out.jl", "in.jl"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("options `--inplace` and `--output` are mutually exclusive", fd2)
+    end
+
+    # runic --check --output=out.jl in.jl
+    let (rc, fd1, fd2) = runic(["--check", "--output=out.jl", "in.jl"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("options `--check` and `--output` are mutually exclusive", fd2)
+    end
+
+    # runic --inplace
+    let (rc, fd1, fd2) = runic(["--inplace"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("option `--inplace` can not be used together with stdin input", fd2)
+    end
+
+    # runic --output=out.jl in1.jl in2.jl
+    let (rc, fd1, fd2) = runic(["--output=out.jl", "in1.jl", "in2.jl"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("option `--output` can not be used together with multiple input files", fd2)
+    end
+
+    # runic in1.jl in2.jl
+    let (rc, fd1, fd2) = runic(["in1.jl", "in2.jl"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("option `--inplace` or `--check` required with multiple input files", fd2)
+    end
+
+    # runic --diff (with no git)
+    let (rc, fd1, fd2) = withenv(() -> runic(["--diff"]), "PATH" => "")
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("option `--diff` requires `git` to be installed", fd2)
+    end
+
+    # runic in.jl (not readable)
+    cdtmp() do
+        f_in = "in.jl"
+        write(f_in, bad)
+        omode = filemode(f_in)
+        chmod(f_in, omode & (typemax(omode) ⊻ 0o444))
+        rc, fd1, fd2 = runic([f_in])
+        chmod(f_in, omode)
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("could not read input from file", fd2)
+        @test occursin("SystemError: opening file", fd2)
+    end
+
+    # runic doesntexist.jl
+    cdtmp() do
+        rc, fd1, fd2 = runic(["doesntexist.jl"])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("input file does not exist", fd2)
+    end
+
+    # runic -o in.jl in.jl
+    cdtmp() do
+        f_in = "in.jl"
+        write(f_in, bad)
+        rc, fd1, fd2 = runic(["-o", f_in, f_in])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("can not use same file for input and output", fd2)
+    end
+
+    # runic --check unparseable.jl
+    cdtmp() do
+        f_in = "in.jl"
+        write(f_in, "syntax error")
+        rc, fd1, fd2 = runic(["--check", f_in])
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("failed to parse input", fd2)
+    end
+
+    # runic -o readonly.jl in.jl
+    return cdtmp() do
+        f_in = "in.jl"
+        write(f_in, bad)
+        f_out = "readonly.jl"
+        touch(f_out)
+        omode = filemode(f_out)
+        chmod(f_out, omode & (typemax(omode) ⊻ 0o222))
+        rc, fd1, fd2 = runic(["-o", f_out, f_in])
+        chmod(f_out, omode)
+        @test rc == 1
+        @test isempty(fd1)
+        @test occursin("could not write to output file", fd2)
+    end
+end
+
+# rc = let argv = pushfirst!(copy(argv), "runic"), argc = length(argv) % Cint
+#     GC.@preserve argv begin
+#         argvptr = Base.unsafe_convert(Ptr{Ptr{UInt8}}, Base.cconvert(Ptr{Ptr{UInt8}}, argv))
+#         redirect_stdio(() -> Main.RunicC.main(argc, argvptr); stdin, stdout, stderr)
+#     end
+# end
diff --git a/test/runtests.jl b/test/runtests.jl
index a6559d8..8864066 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -1455,359 +1455,61 @@ end
     end
 end
 
-@testset "Runic.main" begin
-    bad = "1+1"
-    good = "1 + 1\n"
-
-    # Utils
-    function cdtmp(f)
-        return mktempdir(tmp -> cd(f, tmp))
-    end
-    function runic(std_in::String)
-        return runic(String[], std_in)
-    end
-    function runic(argv::Vector{String} = String[], std_in::String = "")
-        rc, stdout_str, stderr_str = mktemp() do stdin_path, stdin
-            write(stdin_path, std_in)
-            mktemp() do stdout_path, stdout
-                mktemp() do stderr_path, stderr
-                    rc = redirect_stdio(() -> Runic.main(copy(argv)); stdin, stdout, stderr)
-                    close(stderr)
-                    close(stdout)
-                    return rc, read(stdout_path, String), read(stderr_path, String)
-                end
-            end
-        end
-        return rc, stdout_str, stderr_str
-    end
-
-    # runic --help
-    let (rc, fd1, fd2) = runic(["--help"])
-        @test rc == 0
-        @test occursin("Runic.main - format Julia source code", fd1)
-        @test isempty(fd2)
-    end
-
-    # runic --version
-    let (rc, fd1, fd2) = runic(["--version"])
-        @test rc == 0
-        @test occursin("runic version $(Runic.RUNIC_VERSION), julia version $(VERSION)", fd1)
-        @test isempty(fd2)
-    end
-
-    # runic <stdin >stdout
-    for argv in [
-            String[], ["-"],
-            ["--output=-"], ["-o", "-"],
-            ["--output=-", "-"], ["-o", "-", "-"],
-        ]
-        rc, fd1, fd2 = runic(argv, bad)
-        @test rc == 0
-        @test occursin(good, fd1)
-        @test isempty(fd2)
-    end
-
-    # runic --output=out.jl <stdin
-    cdtmp() do
-        f_out = "out.jl"
-        for argv in [
-                ["--output=$f_out"], ["-o", f_out],
-                ["--output=$f_out", "-"], ["-o", f_out, "-"],
-            ]
-            rm(f_out, force = true)
-            rc, fd1, fd2 = runic(argv, bad)
-            @test rc == 0
-            @test isempty(fd1)
-            @test isempty(fd2)
-            @test read(f_out, String) == good
-        end
-    end
-
-    # runic in.jl >stdout
-    cdtmp() do
-        f_in = "in.jl"
-        write(f_in, bad)
-        for argv in [[f_in], ["--output=-", f_in], ["-o", "-", f_in]]
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 0
-            @test occursin(good, fd1)
-            @test isempty(fd2)
-            @test read(f_in, String) == bad
-        end
-    end
-
-    # runic --output=out.jl in.jl
-    cdtmp() do
-        f_in = "in.jl"
-        write(f_in, bad)
-        f_out = "out.jl"
-        for argv in [["--output=$f_out", f_in], ["-o", f_out, f_in]]
-            rm(f_out, force = true)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 0
-            @test isempty(fd1)
-            @test occursin("Formatting `in.jl` -> `out.jl` ...", fd2)
-            @test occursin("✔", fd2)
-            @test !occursin("✖", fd2)
-            @test read(f_out, String) == good
-            @test read(f_in, String) == bad
-        end
-    end
-
-    # runic --inplace in.jl (bad input)
-    cdtmp() do
-        f_in = "in.jl"
-        for argv in [["--inplace", f_in], ["-i", f_in]]
-            write(f_in, bad)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 0
-            @test isempty(fd1)
-            @test occursin("Formatting `in.jl` ...", fd2)
-            @test occursin("✔", fd2)
-            @test !occursin("✖", fd2)
-            @test read(f_in, String) == good
-        end
-    end
-
-    # runic --inplace in.jl (good input)
-    cdtmp() do
-        f_in = "in.jl"
-        for argv in [["--inplace", f_in], ["-i", f_in]]
-            write(f_in, good)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 0
-            @test isempty(fd1)
-            @test occursin("Formatting `in.jl` ...", fd2)
-            @test occursin("✔", fd2)
-            @test !occursin("✖", fd2)
-            @test read(f_in, String) == good
-        end
-    end
-
-    # runic --inplace in/
-    cdtmp() do
-        fgood = "good.jl"
-        mkdir("src")
-        fbad = joinpath("src", "bad.jl")
-        mkdir(".git")
-        gitfile = joinpath(".git", "git.jl")
-        write(gitfile, "this is not a Julia file")
-        markdownfile = "markdown.md"
-        write(markdownfile, "this is not a Julia file")
-        for argv in [["--inplace", "."], ["-i", "."], ["-i", ".", "src"]]
-            write(fgood, good)
-            write(fbad, bad)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 0
-            @test isempty(fd1)
-            @test occursin("Formatting `good.jl` ...", fd2)
-            @test occursin("Formatting `src/bad.jl` ...", fd2)
-            @test occursin("✔", fd2)
-            @test !occursin("✖", fd2)
-            @test !occursin("git.jl", fd2)
-            @test !occursin("markdown.jl", fd2)
-            @test read(fgood, String) == read(fbad, String) == good
-        end
+module RunicMain1
+    using Test: @testset
+    using Runic: main
+    include("maintests.jl")
+    @testset "Runic.main (JIT compiled)" begin
+        maintests(main)
     end
+end
 
-    # runic --check in.jl (bad input)
-    cdtmp() do
-        f_in = "in.jl"
-        for argv in [["--check", f_in], ["-c", f_in]]
-            write(f_in, bad)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 1
-            @test isempty(fd1)
-            @test occursin("Checking `in.jl` ...", fd2)
-            @test !occursin("✔", fd2)
-            @test occursin("✖", fd2)
-            @test read(f_in, String) == bad
+module RunicMain2
+    using Test: @testset, @test
+    if VERSION > v"1.12-"
+        include("../juliac/runicc.jl")
+        include("maintests.jl")
+        function juliac_main(argv)
+            pushfirst!(argv, "runic")
+            juliac_main = @cfunction(RunicC.main, Cint, (Cint, Ptr{Ptr{UInt8}}))
+            return @ccall $juliac_main(length(argv)::Cint, argv::Ptr{Ptr{UInt8}})::Cint
         end
-    end
-
-    # runic --check in.jl (good input)
-    cdtmp() do
-        f_in = "in.jl"
-        for argv in [["--check", f_in], ["-c", f_in]]
-            write(f_in, good)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 0
-            @test isempty(fd1)
-            @test occursin("Checking `in.jl` ...", fd2)
-            @test occursin("✔", fd2)
-            @test !occursin("✖", fd2)
-            @test read(f_in, String) == good
+        @testset "RunicC.main (JIT compiled, prefs: juliac = false)" begin
+            @test !Runic.juliac
+            maintests(juliac_main)
         end
     end
+end
 
-    # runic --check in/
-    cdtmp() do
-        fgood = "good.jl"
-        mkdir("src")
-        fbad = joinpath("src", "bad.jl")
-        mkdir(".git")
-        gitfile = joinpath(".git", "git.jl")
-        write(gitfile, "this is not a Julia file")
-        markdownfile = "markdown.md"
-        write(markdownfile, "this is not a Julia file")
-        for argv in [["--check", "."], ["-c", "."]]
-            write(fgood, good)
-            write(fbad, bad)
-            rc, fd1, fd2 = runic(argv)
-            @test rc == 1
-            @test isempty(fd1)
-            @test occursin("Checking `good.jl` ...", fd2)
-            @test occursin("Checking `src/bad.jl` ...", fd2)
-            @test occursin("✔", fd2)
-            @test occursin("✖", fd2)
-            @test !occursin("git.jl", fd2)
-            @test !occursin("markdown.jl", fd2)
-            @test read(fgood, String) == good
-            @test read(fbad, String) == bad
+module RunicMain3
+    if VERSION > v"1.12-"
+        julia_cmd = Base.julia_cmd()
+        juliac_dir = joinpath(@__DIR__, "..", "juliac")
+        # Instantiate
+        run(
+            addenv(
+                setenv(`make JULIA=$(julia_cmd[1]) Manifest.toml`; dir = juliac_dir),
+                "JULIA_LOAD_PATH" => nothing,
+                "JULIA_PROJECT" => nothing,
+            )
+        )
+        # Run tests
+        code = """
+        using Test: @testset, @test
+        include("runicc.jl")
+        include("../test/maintests.jl")
+        function juliac_main(argv)
+            pushfirst!(argv, "runic")
+            juliac_main = @cfunction(RunicC.main, Cint, (Cint, Ptr{Ptr{UInt8}}))
+            @ccall \$juliac_main(length(argv)::Cint, argv::Ptr{Ptr{UInt8}})::Cint
         end
-    end
-
-    # runic --check --diff in.jl
-    if Sys.which("git") !== nothing
-        cdtmp() do
-            f_in = "in.jl"
-            for argv in [["--check", "--diff", f_in], ["-c", "-d", f_in]]
-                write(f_in, bad)
-                rc, fd1, fd2 = runic(argv)
-                @test rc == 1
-                @test isempty(fd1)
-                @test occursin("Checking `in.jl` ...", fd2)
-                @test !occursin("✔", fd2)
-                @test occursin("✖", fd2)
-                @test occursin("diff --git", fd2)
-                @test occursin("-1+1", fd2)
-                @test occursin("+1 + 1", fd2)
-                @test read(f_in, String) == bad
-            end
+        @testset "RunicC.main (JIT compiled, prefs: juliac = true)" begin
+            @test Runic.juliac
+            maintests(juliac_main)
         end
+        """
+        run(setenv(`$(julia_cmd) --project -e $(code)`; dir = juliac_dir))
     end
-
-    # Error paths
-    # runic -o
-    let (rc, fd1, fd2) = runic(["-o"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("expected output file argument after `-o`", fd2)
-    end
-
-    # runic in.jl -
-    let (rc, fd1, fd2) = runic(["in.jl", "-"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("input `-` can not be used with multiple files", fd2)
-    end
-
-    # runic --inplace --check (TODO: perhaps this should be allowed?)
-    let (rc, fd1, fd2) = runic(["--inplace", "--check"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("options `--inplace` and `--check` are mutually exclusive", fd2)
-    end
-
-    # runic --inplace --output=out.jl in.jl
-    let (rc, fd1, fd2) = runic(["--inplace", "--output=out.jl", "in.jl"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("options `--inplace` and `--output` are mutually exclusive", fd2)
-    end
-
-    # runic --check --output=out.jl in.jl
-    let (rc, fd1, fd2) = runic(["--check", "--output=out.jl", "in.jl"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("options `--check` and `--output` are mutually exclusive", fd2)
-    end
-
-    # runic --inplace
-    let (rc, fd1, fd2) = runic(["--inplace"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("option `--inplace` can not be used together with stdin input", fd2)
-    end
-
-    # runic --output=out.jl in1.jl in2.jl
-    let (rc, fd1, fd2) = runic(["--output=out.jl", "in1.jl", "in2.jl"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("option `--output` can not be used together with multiple input files", fd2)
-    end
-
-    # runic in1.jl in2.jl
-    let (rc, fd1, fd2) = runic(["in1.jl", "in2.jl"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("option `--inplace` or `--check` required with multiple input files", fd2)
-    end
-
-    # runic --diff (with no git)
-    let (rc, fd1, fd2) = withenv(() -> runic(["--diff"]), "PATH" => "")
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("option `--diff` requires `git` to be installed", fd2)
-    end
-
-    # runic in.jl (not readable)
-    cdtmp() do
-        f_in = "in.jl"
-        write(f_in, bad)
-        omode = filemode(f_in)
-        chmod(f_in, omode & (typemax(omode) ⊻ 0o444))
-        rc, fd1, fd2 = runic([f_in])
-        chmod(f_in, omode)
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("could not read input from file", fd2)
-        @test occursin("SystemError: opening file", fd2)
-    end
-
-    # runic doesntexist.jl
-    cdtmp() do
-        rc, fd1, fd2 = runic(["doesntexist.jl"])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("input file does not exist", fd2)
-    end
-
-    # runic -o in.jl in.jl
-    cdtmp() do
-        f_in = "in.jl"
-        write(f_in, bad)
-        rc, fd1, fd2 = runic(["-o", f_in, f_in])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("can not use same file for input and output", fd2)
-    end
-
-    # runic --check unparseable.jl
-    cdtmp() do
-        f_in = "in.jl"
-        write(f_in, "syntax error")
-        rc, fd1, fd2 = runic(["--check", f_in])
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("failed to parse input", fd2)
-    end
-
-    # runic -o readonly.jl in.jl
-    cdtmp() do
-        f_in = "in.jl"
-        write(f_in, bad)
-        f_out = "readonly.jl"
-        touch(f_out)
-        omode = filemode(f_out)
-        chmod(f_out, omode & (typemax(omode) ⊻ 0o222))
-        rc, fd1, fd2 = runic(["-o", f_out, f_in])
-        chmod(f_out, omode)
-        @test rc == 1
-        @test isempty(fd1)
-        @test occursin("could not write to output file", fd2)
-    end
-
 end
 
 const share_julia = joinpath(Sys.BINDIR, Base.DATAROOTDIR, "julia")