Recreating environments (#132)

* Added Conda.freeze and Conda.create functions for re-creating environments.

* Support IO for create and freeze.

* Renamed freeze to export_list.

* Fix docstrings

* Rename create to import_list

src/Conda.jl

@@ -224,6 +224,23 @@ function list(env::Environment=ROOTENV)
     runconda(`list`, env)
 end
 
+"""
+    export_list(filepath, env=$ROOTENV)
+    export_list(io, env=$ROOTENV)
+
+List all packages and write them to an export file for use the Conda.import_list
+"""
+function export_list(filepath::AbstractString, env::Environment=ROOTENV)
+    _install_conda(env)
+    open(filepath, "w") do fobj
+        export_list(fobj, env)
+    end
+end
+
+function export_list(io::IO, env::Environment=ROOTENV)
+    write(io, read(_set_conda_env(`$conda list --export`, env)))
+end
+
 "Get the exact version of a package as a `VersionNumber`."
 function version(name::AbstractString, env::Environment=ROOTENV)
     packages = parseconda(`list`, env)
@@ -318,4 +335,30 @@ function clean(;
     run(_set_conda_env(cmd))
 end
 
+""""
+    import_list(filename, env=$ROOTENV, channels=String[])
+    import_list(io, env=$ROOTENV, channels=String[])
+
+Create a new environment with various channels and a packages list file.
+"""
+function import_list(
+    filepath::AbstractString,
+    env::Environment=ROOTENV;
+    channels=String[]
+)
+    channel_str = ["-c $channel" for channel in channels]
+    run(_set_conda_env(
+        `$conda create $(_quiet()) -y -p $(prefix(env)) $channel_str --file $filepath`,
+        env
+    ))
+end
+
+function import_list(io::IO, args...; kwargs...)
+    mktemp() do path, fobj
+        write(fobj, read(io))
+        close(fobj)
+        import_list(path, args...; kwargs...)
+    end
+end
+
 end

test/runtests.jl

@@ -63,3 +63,21 @@ end
 
 # Run conda clean
 Conda.clean(; debug=true)
+
+@testset "Exporting and creating environments" begin
+    new_env = :test_conda_jl_2
+    Conda.add("curl", env)
+    Conda.export_list("conda-pkg.txt", env)
+
+    # Create a new environment
+    rm(Conda.prefix(new_env); force=true, recursive=true)
+    Conda.import_list(
+        IOBuffer(read("conda-pkg.txt")), new_env; channels=["defaults", "conda-forge"]
+    )
+
+    # Ensure that our new environment has our channels and package installed.
+    Conda.channels(new_env) == ["defaults", "conda-forge"]
+    installed = Conda._installed_packages(new_env)
+    @test "curl" ∈ installed
+    rm("conda-pkg.txt")
+end