Fix issue in CSV.write for empty strings; fixes #515

.travis.yml

@@ -1,3 +1,10 @@
+before_install:
+  - cd ../..
+  - mv $TRAVIS_REPO_SLUG _old
+  - git config --global core.autocrlf false
+  - git clone --depth=50 _old $TRAVIS_REPO_SLUG
+  - cd $TRAVIS_REPO_SLUG
+
 language: julia
 
 sudo: false
@@ -13,7 +20,6 @@ arch:
 
 julia:
   - 1.0
-  - 1.2
   - 1.3
   - nightly
 
@@ -31,12 +37,12 @@ notifications:
   email: false
 
 after_success:
-   - julia -e 'ENV["TRAVIS_JULIA_VERSION"] != "1.1" && ENV["TRAVIS_OS_NAME"] != "linux" && exit(); using Pkg; Pkg.add("Coverage"); using Coverage; Codecov.submit(Codecov.process_folder())'
+   - julia -e 'ENV["TRAVIS_JULIA_VERSION"] == "1.3" && ENV["TRAVIS_OS_NAME"] != "linux" && exit(); using Pkg; Pkg.add("Coverage"); using Coverage; Codecov.submit(Codecov.process_folder())'
 
 jobs:
   include:
     - stage: "Documentation"
-      julia: 1.2
+      julia: 1.3
       os: linux
       script:
         - julia --project=docs/ -e 'using Pkg; Pkg.develop(PackageSpec(path=pwd())); Pkg.instantiate(); Pkg.build("CSV")'

Project.toml

@@ -32,4 +32,4 @@ Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Test", "CodecZlib"]
+test = ["Test", "Random", "CodecZlib"]

src/write.jl

@@ -322,6 +322,7 @@ function writecell(buf, pos, len, io, x::AbstractString, opts)
 end
 
 function check(bytes, sz, delim::UInt8, oq, cq, newline::UInt8)
+    isempty(bytes) && return false, false
     needtoescape = false
     @inbounds needtoquote = bytes[1] == oq
     @simd for i = 1:sz

test/write.jl

@@ -197,4 +197,10 @@ using CSV, Dates, WeakRefStrings, CategoricalArrays, Tables
     end
 
     @test read(rd, String) == "col1,col2,col3\n1,4,7\n2,5,8\n3,6,9\n"
-end
+
+    # issue 515
+    io = IOBuffer()
+    (col1=[""],) |> CSV.write(io)
+    @test String(take!(io)) == "col1\n\n"
+
+end # @testset "CSV.write"