Keep extra indent for short single case DU. Fixes #1122 and #1123. (#…

…1125)

src/Fantomas.Tests/ModuleTests.fs

@@ -544,3 +544,59 @@ namespace Foo
 
 do ()
 """
+
+[<Test>]
+let ``keep correct indentation for let binding inside nested module, 1122`` () =
+    formatSourceString false """
+namespace Test
+
+module App =
+    type Msg = B of C
+
+    let a = "test"
+"""  config
+    |> prepend newline
+    |> should equal """
+namespace Test
+
+module App =
+    type Msg = B of C
+
+    let a = "test"
+"""
+
+[<Test>]
+let ``keep correct indentation for let binding inside nested module, signature file`` () =
+    formatSourceString true """
+namespace Test
+
+module App =
+    type Msg = B of C
+
+    val a : string
+"""  config
+    |> prepend newline
+    |> should equal """
+namespace Test
+
+module App =
+    type Msg = B of C
+
+    val a: string
+"""
+
+[<Test>]
+let ``nested nested module with single union DU, 1123`` () =
+    formatSourceString false """
+module Test =
+  module Foo =
+    type t = T of bool
+    let foo = true
+"""  config
+    |> prepend newline
+    |> should equal """
+module Test =
+    module Foo =
+        type t = T of bool
+        let foo = true
+"""

src/Fantomas/CodePrinter.fs

@@ -2997,7 +2997,7 @@ and genTypeDefn astContext (TypeDef (ats, px, ao, tds, tcs, tdr, ms, s, preferPo
                                    HasVerticalBar = hasVerticalBar }
                                 x)
 
-                expressionFitsOnRestOfLine (sepSpace +> expr) (indent +> sepNln +> expr) ctx
+                expressionFitsOnRestOfLine (indent +> sepSpace +> expr) (indent +> sepNln +> expr) ctx
             | xs ->
                 indent
                 +> sepNln
@@ -3324,7 +3324,7 @@ and genSigTypeDefn astContext (SigTypeDef (ats, px, ao, tds, tcs, tdr, ms, s, pr
                                    HasVerticalBar = hasVerticalBar }
                                 x)
 
-                expressionFitsOnRestOfLine (sepSpace +> expr) (indent +> sepNln +> expr)
+                expressionFitsOnRestOfLine (indent +> sepSpace +> expr) (indent +> sepNln +> expr)
             | xs ->
                 indent
                 +> sepNln