Expand uconvert tests

Author: MilesCranmer

src/symbolic_dimensions.jl

@@ -113,7 +113,8 @@ expand_units(q::QuantityArray) = expand_units.(q)
 Convert a quantity `q` with base SI units to the symbolic units of `qout`, for `q` and `qout` with compatible units.
 Mathematically, the result has value `q / expand_units(qout)` and units `dimension(qout)`. 
 """
-function uconvert(qout::AbstractQuantity{<:Any, <:SymbolicDimensions}, q::AbstractQuantity{<:Any, <:Dimensions})
+function uconvert(qout::AbstractQuantity{T, <:SymbolicDimensions}, q::AbstractQuantity{<:Any, <:Dimensions}) where {T}
+    isone(ustrip(qout)) || error("You passed a quantity with a non-unit value to uconvert.")
     qout_expanded = expand_units(qout)
     dimension(q) == dimension(qout_expanded) || throw(DimensionError(q, qout_expanded))
     return new_quantity(typeof(qout), ustrip(q) / ustrip(qout_expanded), dimension(qout))

test/unittests.jl

@@ -569,9 +569,6 @@ end
     @test us"Constants.h" != us"h"
     @test expand_units(us"Constants.h") == u"Constants.h"
 
-    @test uconvert(us"nm", 5e-9u"m") ≈ (5e-9u"m" |> uconvert(us"nm")) ≈ 5us"nm"
-    @test_throws DimensionError uconvert(us"nm * J", 5e-9u"m")
-
     # Actually expands to:
     @test dimension(us"Constants.h")[:m] == 2
     @test dimension(us"Constants.h")[:s] == -1
@@ -594,6 +591,22 @@ end
         @test_throws "rad is not available as a symbol" sym5.rad
 end
 
+@testset "uconvert" begin
+    @test uconvert(us"nm", 5e-9u"m") ≈ (5e-9u"m" |> uconvert(us"nm")) ≈ 5us"nm"
+    @test_throws DimensionError uconvert(us"nm * J", 5e-9u"m")
+
+    q = 1.5u"Constants.M_sun"
+    qs = uconvert(us"Constants.M_sun", 5.0 * q)
+    @test qs ≈ 7.5us"Constants.M_sun"
+    @test dimension(qs)[:kg] == 0
+    @test dimension(qs)[:g] == 0
+    @test dimension(qs)[:M_sun] == 1
+    @test expand_units(qs) ≈ 5.0 * q
+
+    # Refuses to convert to non-unit quantities:
+    @test_throws ErrorException uconvert(1.2us"m", 1.0u"m")
+end
+
 @testset "Test ambiguities" begin
     R = DEFAULT_DIM_BASE_TYPE
     x = convert(R, 10)