diff --git a/test/output.jl b/test/output.jl
new file mode 100644
index 000000000..dbfcdb121
--- /dev/null
+++ b/test/output.jl
@@ -0,0 +1,138 @@
+@testset "output" begin
+
+    @testset "formatted output" begin
+        _, out = @grab_output @on_device @mtlprintf("")
+        @test out == ""
+    
+        _, out = @grab_output @on_device @mtlprintf("Testing...\n")
+        @test out == "Testing...\n"
+    
+        # narrow integer
+        _, out = @grab_output @on_device @mtlprintf("Testing %d %d...\n", Int32(1), Int32(2))
+        @test out == "Testing 1 2...\n"
+    
+        # wide integer
+        _, out = @grab_output @on_device @mtlprintf("Testing %ld %ld...\n", Int64(1), Int64(2))
+        @test out == "Testing 1 2...\n"
+    
+        _, out = @grab_output @on_device begin
+            @mtlprintf("foo")
+            @mtlprintf("bar\n")
+        end
+        @test out == "foobar\n"
+    
+        # c argument promotions
+        function kernel(A)
+            @mtlprintf("%f %f\n", A[1], A[1])
+            return
+        end
+        x = mtl(ones(2, 2))
+        _, out = @grab_output begin
+            Metal.@sync @metal kernel(x)
+        end
+        @test out == "1.000000 1.000000\n"
+    end
+    
+    @testset "@mtlprint" begin
+        # basic @mtlprint/@mtlprintln
+    
+        _, out = @grab_output @on_device @mtlprint("Hello, World\n")
+        @test out == "Hello, World\n"
+    
+        _, out = @grab_output @on_device @mtlprintln("Hello, World")
+        @test out == "Hello, World\n"
+    
+    
+        # argument interpolation (by the macro, so can use literals)
+    
+        _, out = @grab_output @on_device @mtlprint("foobar")
+        @test out == "foobar"
+    
+        _, out = @grab_output @on_device @mtlprint(:foobar)
+        @test out == "foobar"
+    
+        _, out = @grab_output @on_device @mtlprint("foo", "bar")
+        @test out == "foobar"
+    
+        _, out = @grab_output @on_device @mtlprint("foobar ", 42)
+        @test out == "foobar 42"
+    
+        _, out = @grab_output @on_device @mtlprint("foobar $(42)")
+        @test out == "foobar 42"
+    
+        _, out = @grab_output @on_device @mtlprint("foobar $(4)", 2)
+        @test out == "foobar 42"
+    
+        _, out = @grab_output @on_device @mtlprint("foobar ", 4, "$(2)")
+        @test out == "foobar 42"
+    
+        _, out = @grab_output @on_device @mtlprint(42)
+        @test out == "42"
+    
+        _, out = @grab_output @on_device @mtlprint(4, 2)
+        @test out == "42"
+    
+        _, out = @grab_output @on_device @mtlprint(Any)
+        @test out == "Any"
+    
+        _, out = @grab_output @on_device @mtlprintln("foobar $(42)")
+        @test out == "foobar 42\n"
+    
+    
+        # argument types
+    
+        # we're testing the generated functions now, so can't use literals
+        function test_output(val, str)
+            canary = rand(Int32) # if we mess up the main arg, this one will print wrong
+            _, out = @grab_output @on_device @mtlprint(val, " (", canary, ")")
+            @test out == "$(str) ($(Int(canary)))"
+        end
+    
+        for typ in (Int16, Int32, Int64, UInt16, UInt32, UInt64)
+            test_output(typ(42), "42")
+        end
+    
+        for typ in (Float32,)
+            test_output(typ(42), "42.000000")
+        end
+    
+        test_output(Cchar('c'), "c")
+    
+        for typ in (Ptr{Cvoid}, Ptr{Int})
+            ptr = convert(typ, Int(0x12345))
+            test_output(ptr, "0x12345")
+        end
+    
+        test_output(true, "1")
+        test_output(false, "0")
+    
+        test_output((1,), "(1,)")
+        test_output((1,2), "(1, 2)")
+        test_output((1,2,3.0f0), "(1, 2, 3.000000)")
+    
+        # escaping
+    
+        kernel1(val) = (@mtlprint(val); nothing)
+        _, out = @grab_output @on_device kernel1(42)
+        @test out == "42"
+    
+        kernel2(val) = (@mtlprintln(val); nothing)
+        _, out = @grab_output @on_device kernel2(42)
+        @test out == "42\n"
+    end
+    
+    @testset "@mtlshow" begin
+        function kernel()
+            seven_i32 = Int32(7)
+            three_f32 = Float32(3)
+            @mtlshow seven_i32
+            @mtlshow three_f32
+            @mtlshow 1f0 + 4f0
+            return
+        end
+    
+        _, out = @grab_output @on_device kernel()
+        @test out == "seven_i32 = 7\nthree_f32 = 3.000000\n1.0f0 + 4.0f0 = 5.000000\n"
+    end
+end
+    
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