Fix dotnet sln project type

The presence of an "src/" directory doesn't say anything about the
type of the project. This commit fixes the dotnet sln project type to
rely on the presence of an .sln file instead of the "src/" directory.

CHANGELOG.md

@@ -3,6 +3,9 @@
 ## master (unreleased)
 
 * [#1910](https://github.com/bbatsov/projectile/pull/1910): Reverts [#1895](https://github.com/bbatsov/projectile/pull/1895) as those changes appear to cause a significant performance regression across a number of use-cases.
+* [#1915](https://github.com/bbatsov/projectile/pull/1915): Fix
+  dotnet-sln project-type recognition (check `*.sln` files instead of
+  `src/`)
 
 ### New features
 

projectile.el

@@ -3058,6 +3058,12 @@ it acts on the current project."
   (or (projectile-verify-file-wildcard "?*.csproj" dir)
       (projectile-verify-file-wildcard "?*.fsproj" dir)))
 
+(defun projectile-dotnet-sln-project-p (&optional dir)
+  "Check if a project contains a .NET solution project marker.
+When DIR is specified it checks DIR's project, otherwise
+it acts on the current project."
+  (or (projectile-verify-file-wildcard "?*.sln" dir)))
+
 (defun projectile-go-project-p (&optional dir)
   "Check if a project contains Go source files.
 When DIR is specified it checks DIR's project, otherwise
@@ -3271,7 +3277,7 @@ a manual COMMAND-TYPE command is created with
                                   :compile "dotnet build"
                                   :run "dotnet run"
                                   :test "dotnet test")
-(projectile-register-project-type 'dotnet-sln '("src")
+(projectile-register-project-type 'dotnet-sln #'projectile-dotnet-sln-project-p
                                   :project-file "?*.sln"
                                   :compile "dotnet build"
                                   :run "dotnet run"

test/projectile-test.el

@@ -1347,11 +1347,11 @@ Just delegates OPERATION and ARGS for all operations except for`shell-command`'.
       (let ((projectile-indexing-method 'native))
         (spy-on 'projectile-project-root :and-return-value (file-truename (expand-file-name "project/")))
         (expect (projectile-detect-project-type) :to-equal 'emacs-eldev)))))
-  (it "detects project-type for projects with src dir and no other marker"
+  (it "detects project-type for dotnet sln projects"
     (projectile-test-with-sandbox
      (projectile-test-with-files
       ("project/"
-       "project/src/")
+       "project/Project.sln")
       (let ((projectile-indexing-method 'native))
         (spy-on 'projectile-project-root :and-return-value (file-truename (expand-file-name "project/")))
         (expect (projectile-detect-project-type) :to-equal 'dotnet-sln)))))