Fix Base.one(::Angle2d) method and etc. (#195)

* Base.one(r::Rotation) = one(typeof(r))

* update tests for one(::Rotation)

src/core_types.jl

@@ -23,6 +23,9 @@ Base.zeros(::Type{R}, dims::Base.DimOrInd...) where {R<:Rotation} = zeros(typeof
 Base.zeros(::Type{R}, dims::NTuple{N, Integer}) where {R<:Rotation, N} = zeros(typeof(zero(R)),dims)
 Base.zeros(::Type{R}, dims::Tuple{}) where {R<:Rotation} = zeros(typeof(zero(R)),dims) # avoid ambiguity
 
+# Generate identity rotation matrix
+Base.one(r::Rotation) = one(typeof(r))
+
 # Rotation angles and axes can be obtained by converting to the AngleAxis type
 rotation_angle(r::Rotation{3}) = rotation_angle(AngleAxis(r))
 rotation_axis(r::Rotation{3}) = rotation_axis(AngleAxis(r))

test/2d.jl

@@ -31,7 +31,9 @@ using Unitful
             @test @inferred(size(R)) == (2,2)
             @test @inferred(size(R{Float32})) == (2,2)
             @test one(R)::R == I
+            @test one(one(R))::R == I
             @test one(R{Float32})::R{Float32} == I32
+            @test one(one(R{Float32}))::R{Float32} == I32
         end
     end
 

test/rotation_tests.jl

@@ -98,7 +98,9 @@ all_types = (RotMatrix{3}, AngleAxis, RotationVec,
         @testset "$(R)" for R in all_types
             # one(R) should always return something of type R (#114)
             @test one(R)::R == I
+            @test one(one(R))::R == I
             @test one(R{Float32})::R{Float32} == I32
+            @test one(one(R{Float32}))::R{Float32} == I32
         end
     end