remove tensorflow from ci

.travis.yml

@@ -10,7 +10,6 @@ notifications:
 # uncomment the following lines to override the default test script
 script:
   - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
-  - julia -e 'VERSION < v"0.6-" && Pkg.add("TensorFlow")'
   - julia -e 'Pkg.add("MXNet")'
   - julia -e 'Pkg.clone("https://github.com/MikeInnes/DataFlow.jl")'
   - julia -e 'Pkg.clone(pwd()); Pkg.build("Flux"); Pkg.test("Flux"; coverage=true)'

test/backend.jl

@@ -1,19 +1,19 @@
 xs = rand(20)
 d = Affine(20, 10)
 
-let dt = tf(d)
+@tfonly let dt = tf(d)
   @test d(xs) ≈ dt(xs)
 end
 
-let dm = mxnet(d, (1, 20))
+@mxonly let dm = mxnet(d, (1, 20))
   @test d(xs) ≈ dm(xs)
 end
 
 # TensorFlow native integration
 
-using TensorFlow
+@tfonly let
+  using TensorFlow
 
-let
   sess = TensorFlow.Session()
   X = placeholder(Float32)
   Y = Tensor(d, X)

test/runtests.jl

@@ -5,6 +5,14 @@ using DataFlow: Input, Line, Frame
 syntax(v::Vertex) = prettify(DataFlow.syntax(v))
 syntax(x) = syntax(graph(x))
 
+macro mxonly(ex)
+  :(Base.find_in_path("MXNet") ≠ nothing && $(esc(ex)))
+end
+
+macro tfonly(ex)
+  :(Base.find_in_path("TensorFlow") ≠ nothing && $(esc(ex)))
+end
+
 include("basic.jl")
 include("recurrent.jl")
 include("backend.jl")