fix and test single-face mesh constructor

Author: ffreyer

src/basic_types.jl

@@ -758,6 +758,12 @@ function Mesh(points::AbstractVector{<:Point}, faces::AbstractVector{<:Integer},
     return Mesh(points, connect(faces, facetype, skip))
 end
 
+# the method above allows Mesh(..., Face(...), ...) to work, but produces bad results
+# explicitly error here
+function Mesh(points::AbstractVector{<:Point}, faces::AbstractFace, args...; kwargs...)
+    throw(MethodError(Mesh, (points, faces, args...)))
+end
+
 function Mesh(; kwargs...)
     fs = faces(kwargs[:position]::FaceView)
     va = NamedTuple{keys(kwargs)}(map(keys(kwargs)) do k

test/meshes.jl

@@ -31,6 +31,8 @@ end
 @testset "Merge empty vector of meshes" begin
     # https://github.com/JuliaGeometry/GeometryBasics.jl/issues/136
     merge(Mesh[]) == Mesh(Point3f[], GLTriangleFace[])
+    merge([Mesh(Point3f[], GLTriangleFace[])]) == Mesh(Point3f[], GLTriangleFace[])
+    merge([Mesh(Point3f[], GLTriangleFace[]), Mesh(Point3f[], GLTriangleFace[])]) == Mesh(Point3f[], GLTriangleFace[])
 end
 
 @testset "Vertex Index Remapping" begin
@@ -138,6 +140,8 @@ end
         @test faces(m) == fs
     end
 
+    @test_throws MethodError Mesh(Point2f[], GLTriangleFace(1,2,3))
+
     @testset "Verification" begin
         # enough vertices present
         @test_throws ErrorException Mesh(rand(Point2f, 7), fs)