diff --git a/README.md b/README.md
index 5b891fc..c13d08f 100644
--- a/README.md
+++ b/README.md
@@ -187,6 +187,11 @@ Observe the `OneTimeSetUp` which sets global state to enter "bulk update" mode,
 
 * The snapshot updating mechanism *requires* you to use verbatim string literals. While the test assertions will work correctly if you do `snapshot ("foo" + "bar" + f 3)`, for example, the updating code is liable to do something undefined in that case. Also do not use format strings (`$"blah"`).
 
+# Output formats
+
+* The `Diff` module provides a Patience diff and a Myers diff implementation, which you can use to make certain tests much more readable.
+* The `Dot` module provides `render`, which renders a dot file as ASCII art. You will need `graph-easy` to use this feature.
+
 # Licence
 
 MIT.
diff --git a/WoofWare.Expect.Test/TestDot.fs b/WoofWare.Expect.Test/TestDot.fs
new file mode 100644
index 0000000..19b927e
--- /dev/null
+++ b/WoofWare.Expect.Test/TestDot.fs
@@ -0,0 +1,104 @@
+namespace WoofWare.Expect.Test
+
+#nowarn 0044 // This construct is deprecated
+
+open System
+open FsUnitTyped
+open WoofWare.Expect
+open NUnit.Framework
+open System.IO.Abstractions
+open System.IO.Abstractions.TestingHelpers
+
+[<TestFixture>]
+module TestDot =
+    let toFs (fs : IFileSystem) : Dot.IFileSystem =
+        { new Dot.IFileSystem with
+            member _.DeleteFile s = fs.File.Delete s
+            member _.WriteFile path contents = fs.File.WriteAllText (path, contents)
+            member _.GetTempFileName () = fs.Path.GetTempFileName ()
+        }
+
+    [<Test ; Explicit "requires graph-easy dependency">]
+    let ``Basic dotfile, real graph-easy`` () =
+        let s =
+            """digraph G {
+  rankdir = TB
+  bgcolor = transparent
+    n2 [shape=box label="{{n2|Map|height=1}}" ]
+    n1 [shape=box label="{{n1|Const|height=0}}" ]
+  n1 -> n2
+}"""
+
+        expect {
+            snapshot
+                @"
+┌───────────────────────┐
+│ {{n1|Const|height=0}} │
+└───────────────────────┘
+  │
+  │
+  ▼
+┌───────────────────────┐
+│  {{n2|Map|height=1}}  │
+└───────────────────────┘
+"
+
+            return Dot.render s
+        }
+
+    [<Test>]
+    let ``Basic dotfile`` () =
+        let fs = MockFileSystem ()
+
+        let contents =
+            """digraph G {
+  rankdir = TB
+  bgcolor = transparent
+    n2 [shape=box label="{{n2|Map|height=1}}" ]
+    n1 [shape=box label="{{n1|Const|height=0}}" ]
+  n1 -> n2
+}"""
+
+        let mutable started = false
+        let mutable waited = false
+        let mutable disposed = false
+
+        let expected =
+            "┌───────────────────────┐
+│ {{n1|Const|height=0}} │
+└───────────────────────┘
+  │
+  │
+  ▼
+┌───────────────────────┐
+│  {{n2|Map|height=1}}  │
+└───────────────────────┘
+"
+
+        let pr =
+            { new Dot.IProcess<IDisposable> with
+                member _.Start _ =
+                    started <- true
+                    true
+
+                member _.Create exe args =
+                    exe |> shouldEqual "graph-easy"
+
+                    args.StartsWith ("--as=boxarg --from=dot ", StringComparison.Ordinal)
+                    |> shouldEqual true
+
+                    { new IDisposable with
+                        member _.Dispose () = disposed <- true
+                    }
+
+                member _.WaitForExit p = waited <- true
+                member _.ReadStandardOutput _ = expected
+            }
+
+        Dot.render' pr (toFs fs) "graph-easy" contents
+        |> _.TrimStart()
+        |> shouldEqual expected
+
+        started |> shouldEqual true
+        waited |> shouldEqual true
+        disposed |> shouldEqual true
diff --git a/WoofWare.Expect.Test/WoofWare.Expect.Test.fsproj b/WoofWare.Expect.Test/WoofWare.Expect.Test.fsproj
index f69066a..c40c2ba 100644
--- a/WoofWare.Expect.Test/WoofWare.Expect.Test.fsproj
+++ b/WoofWare.Expect.Test/WoofWare.Expect.Test.fsproj
@@ -14,6 +14,7 @@
       <Compile Include="BulkUpdateExample.fs" />
       <Compile Include="SimpleTest.fs" />
       <Compile Include="TestDiff.fs" />
+      <Compile Include="TestDot.fs" />
       <Compile Include="TestExceptionThrowing.fs" />
       <Compile Include="TestSurface.fs" />
       <Compile Include="TestSnapshotFinding\TestSnapshotFinding.fs" />
@@ -40,6 +41,9 @@
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1"/>
         <PackageReference Include="NUnit" Version="4.3.2"/>
         <PackageReference Include="NUnit3TestAdapter" Version="5.0.0"/>
+      <!-- TODO: when ApiSurface accepts https://github.com/G-Research/ApiSurface/pull/116, upgrade these -->
+        <PackageReference Include="System.IO.Abstractions" Version="4.2.13" />
+        <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="4.2.13" />
     </ItemGroup>
 
     <ItemGroup>
diff --git a/WoofWare.Expect/Dot.fs b/WoofWare.Expect/Dot.fs
new file mode 100644
index 0000000..cf46ee0
--- /dev/null
+++ b/WoofWare.Expect/Dot.fs
@@ -0,0 +1,82 @@
+namespace WoofWare.Expect
+
+open System
+open System.Diagnostics
+open System.IO
+
+/// Methods for rendering dot files (specifications of graphs).
+[<RequireQualifiedAccess>]
+module Dot =
+    /// A mock for System.Diagnostics.Process.
+    type IProcess<'Process when 'Process :> IDisposable> =
+        /// Equivalent to Process.Create
+        abstract Create : exe : string -> args : string -> 'Process
+        /// Equivalent to Process.Start
+        abstract Start : 'Process -> bool
+        /// Equivalent to Process.WaitForExit
+        abstract WaitForExit : 'Process -> unit
+        /// Equivalent to Process.StandardOutput.ReadToEnd
+        abstract ReadStandardOutput : 'Process -> string
+
+    /// The real Process interface, in a form that can be passed to `render'`.
+    let process' =
+        { new IProcess<Process> with
+            member _.Create exe args =
+                let psi = ProcessStartInfo exe
+                psi.RedirectStandardOutput <- true
+                psi.Arguments <- args
+                let result = new Process ()
+                result.StartInfo <- psi
+                result
+
+            member _.Start p = p.Start ()
+            member _.WaitForExit p = p.WaitForExit ()
+            member _.ReadStandardOutput p = p.StandardOutput.ReadToEnd ()
+        }
+
+    /// A mock for System.IO
+    type IFileSystem =
+        /// Equivalent to Path.GetTempFileName
+        abstract GetTempFileName : unit -> string
+        /// Equivalent to File.Delete
+        abstract DeleteFile : string -> unit
+        /// Equivalent to File.WriteAllText (curried)
+        abstract WriteFile : path : string -> contents : string -> unit
+
+    /// The real filesystem, in a form that can be passed to `render'`.
+    let fileSystem =
+        { new IFileSystem with
+            member _.GetTempFileName () = Path.GetTempFileName ()
+            member _.DeleteFile f = File.Delete f
+            member _.WriteFile path contents = File.WriteAllText (path, contents)
+        }
+
+    /// writeFile takes the filepath first and the contents second.
+    /// Due to the impoverished nature of the .NET Standard APIs, you are in charge of making sure the output of
+    /// fs.GetTempFileName is suitable for interpolation into a command line.
+    let render'<'Process when 'Process :> IDisposable>
+        (pr : IProcess<'Process>)
+        (fs : IFileSystem)
+        (graphEasyExecutable : string)
+        (dotFileContents : string)
+        : string
+        =
+        let tempFile = fs.GetTempFileName ()
+
+        try
+            fs.WriteFile tempFile dotFileContents
+
+            use p = pr.Create graphEasyExecutable ("--as=boxarg --from=dot " + tempFile)
+            pr.Start p |> ignore<bool>
+            pr.WaitForExit p
+
+            "\n" + pr.ReadStandardOutput p
+        finally
+            try
+                fs.DeleteFile tempFile
+            with _ ->
+                ()
+
+    /// Call `graph-easy` to render the dotfile as ASCII art.
+    /// This is fully mockable, but you must use `render'` to do so.
+    let render = render' process' fileSystem "graph-easy"
diff --git a/WoofWare.Expect/SurfaceBaseline.txt b/WoofWare.Expect/SurfaceBaseline.txt
index 0741d86..83e3327 100644
--- a/WoofWare.Expect/SurfaceBaseline.txt
+++ b/WoofWare.Expect/SurfaceBaseline.txt
@@ -50,6 +50,23 @@ WoofWare.Expect.DiffOperation.NewDelete [static method]: (int, string) -> WoofWa
 WoofWare.Expect.DiffOperation.NewInsert [static method]: (int, string) -> WoofWare.Expect.DiffOperation
 WoofWare.Expect.DiffOperation.NewMatch [static method]: (int, int, string) -> WoofWare.Expect.DiffOperation
 WoofWare.Expect.DiffOperation.Tag [property]: [read-only] int
+WoofWare.Expect.Dot inherit obj
+WoofWare.Expect.Dot+IFileSystem - interface with 3 member(s)
+WoofWare.Expect.Dot+IFileSystem.DeleteFile [method]: string -> unit
+WoofWare.Expect.Dot+IFileSystem.GetTempFileName [method]: unit -> string
+WoofWare.Expect.Dot+IFileSystem.WriteFile [method]: string -> string -> unit
+WoofWare.Expect.Dot+IProcess`1 - interface with 4 member(s)
+WoofWare.Expect.Dot+IProcess`1.Create [method]: string -> string -> #(IDisposable)
+WoofWare.Expect.Dot+IProcess`1.ReadStandardOutput [method]: #(IDisposable) -> string
+WoofWare.Expect.Dot+IProcess`1.Start [method]: #(IDisposable) -> bool
+WoofWare.Expect.Dot+IProcess`1.WaitForExit [method]: #(IDisposable) -> unit
+WoofWare.Expect.Dot.fileSystem [static property]: [read-only] WoofWare.Expect.Dot+IFileSystem
+WoofWare.Expect.Dot.get_fileSystem [static method]: unit -> WoofWare.Expect.Dot+IFileSystem
+WoofWare.Expect.Dot.get_process' [static method]: unit -> System.Diagnostics.Process WoofWare.Expect.Dot+IProcess
+WoofWare.Expect.Dot.get_render [static method]: unit -> (string -> string)
+WoofWare.Expect.Dot.process' [static property]: [read-only] System.Diagnostics.Process WoofWare.Expect.Dot+IProcess
+WoofWare.Expect.Dot.render [static property]: [read-only] string -> string
+WoofWare.Expect.Dot.render' [static method]: #(IDisposable) WoofWare.Expect.Dot+IProcess -> WoofWare.Expect.Dot+IFileSystem -> string -> string -> string
 WoofWare.Expect.ExpectBuilder inherit obj
 WoofWare.Expect.ExpectBuilder..ctor [constructor]: (string * int)
 WoofWare.Expect.ExpectBuilder..ctor [constructor]: bool
diff --git a/WoofWare.Expect/WoofWare.Expect.fsproj b/WoofWare.Expect/WoofWare.Expect.fsproj
index a612ed1..c9ba90b 100644
--- a/WoofWare.Expect/WoofWare.Expect.fsproj
+++ b/WoofWare.Expect/WoofWare.Expect.fsproj
@@ -20,6 +20,7 @@
         <Compile Include="Text.fs" />
         <Compile Include="File.fs" />
         <Compile Include="Diff.fs" />
+        <Compile Include="Dot.fs" />
         <Compile Include="Domain.fs" />
         <Compile Include="SnapshotUpdate.fs" />
         <Compile Include="Config.fs" />
diff --git a/WoofWare.Expect/version.json b/WoofWare.Expect/version.json
index f68ef4f..1e0fab9 100644
--- a/WoofWare.Expect/version.json
+++ b/WoofWare.Expect/version.json
@@ -1,5 +1,5 @@
 {
-  "version": "0.5",
+  "version": "0.6",
   "publicReleaseRefSpec": [
     "^refs/heads/main$"
   ],
@@ -10,4 +10,4 @@
     ":/Directory.Build.props",
     ":/LICENSE"
   ]
-}
\ No newline at end of file
+}
diff --git a/flake.nix b/flake.nix
index fd7b113..a637461 100644
--- a/flake.nix
+++ b/flake.nix
@@ -66,6 +66,7 @@
           pkgs.nodePackages.markdown-link-check
           pkgs.shellcheck
           pkgs.xmlstarlet
+          pkgs.graph-easy
         ];
       };
     });
diff --git a/nix/deps.json b/nix/deps.json
index 262e636..ad36b7c 100644
--- a/nix/deps.json
+++ b/nix/deps.json
@@ -189,6 +189,11 @@
     "version": "4.2.13",
     "hash": "sha256-nkC/PiqE6+c1HJ2yTwg3x+qdBh844Z8n3ERWDW8k6Gg="
   },
+  {
+    "pname": "System.IO.Abstractions.TestingHelpers",
+    "version": "4.2.13",
+    "hash": "sha256-WGGatXlgyROnptdw0zU3ggf54eD/zusO/fvtf+5wuPU="
+  },
   {
     "pname": "System.IO.FileSystem.AccessControl",
     "version": "4.5.0",