diff --git a/src/API.jl b/src/API.jl
index 834fbdcef5..e8a071cea8 100644
--- a/src/API.jl
+++ b/src/API.jl
@@ -1302,8 +1302,11 @@ function status(ctx::Context, pkgs::Vector{PackageSpec}; diff::Bool=false, mode=
 end
 
 
-function activate(;temp=false, shared=false, prev=false, io::IO=stderr_f())
+function activate(;temp=false, shared=false, prev=false, target::Union{Symbol,Nothing}=nothing, io::IO=stderr_f())
     shared && pkgerror("Must give a name for a shared environment")
+    if target !== nothing
+        return activate(Base.active_project(); target, io)
+    end
     temp && return activate(mktempdir(); io=io)
     if prev
         if isempty(PREV_ENV_PATH[])
@@ -1333,12 +1336,12 @@ function _activate_dep(dep_name::AbstractString)
     uuid = get(ctx.env.project.deps, dep_name, nothing)
     if uuid !== nothing
         entry = manifest_info(ctx.env.manifest, uuid)
-        if entry.path !== nothing
+        if entry !== nothing && entry.path !== nothing
             return joinpath(dirname(ctx.env.manifest_file), entry.path::String)
         end
     end
 end
-function activate(path::AbstractString; shared::Bool=false, temp::Bool=false, io::IO=stderr_f())
+function activate(path::AbstractString; shared::Bool=false, temp::Bool=false, target::Union{Symbol,Nothing}=nothing, io::IO=stderr_f())
     temp && pkgerror("Can not give `path` argument when creating a temporary environment")
     if !shared
         # `pkg> activate path`/`Pkg.activate(path)` does the following
@@ -1370,6 +1373,14 @@ function activate(path::AbstractString; shared::Bool=false, temp::Bool=false, io
             fullpath = joinpath(Pkg.envdir(Pkg.depots1()), path)
         end
     end
+    if target !== nothing
+        printpkgstyle(io, :Creating, "temporary project based on the target `$target` in $(pathrepr(fullpath))", color = Base.info_color())
+        target_project = Operations.gen_target_project(Context(), nothing, fullpath, "test")
+        temp_project_dir = mktempdir()
+        temp_projectfile = joinpath(temp_project_dir, "Project.toml")
+        Types.write_project(target_project, temp_projectfile)
+        fullpath = temp_projectfile
+    end
     if !isnothing(Base.active_project())
         PREV_ENV_PATH[] = Base.active_project()
     end
diff --git a/src/Operations.jl b/src/Operations.jl
index 3fb44792ed..c76acc32bb 100644
--- a/src/Operations.jl
+++ b/src/Operations.jl
@@ -2219,11 +2219,15 @@ function parse_REQUIRE(require_path::String)
 end
 
 # "targets" based test deps -> "test/Project.toml" based deps
-function gen_target_project(ctx::Context, pkg::PackageSpec, source_path::String, target::String)
+function gen_target_project(ctx::Context, pkg::Union{PackageSpec,Nothing}, source_path::String, target::String)
     env = ctx.env
     registries = ctx.registries
     test_project = Types.Project()
     if projectfile_path(source_path; strict=true) === nothing
+        if pkg === nothing
+            # don't support REQUIRE if pkg isn't provided
+            pkgerror("No project file found in $(source_path)")
+        end
         # no project file, assuming this is an old REQUIRE package
         test_project.deps = copy(env.manifest[pkg.uuid].deps)
         if target == "test"
diff --git a/src/REPLMode/argument_parsers.jl b/src/REPLMode/argument_parsers.jl
index 5d909e91ba..e0db38124d 100644
--- a/src/REPLMode/argument_parsers.jl
+++ b/src/REPLMode/argument_parsers.jl
@@ -218,6 +218,7 @@ end
 #
 function parse_activate(args::Vector{QString}, options)
     isempty(args) && return [] # nothing to do
+    args = filter(a -> !in(a.raw, ("--test", "--build")), args)
     if length(args) == 1
         x = first(args)
         if x.isquoted
diff --git a/src/REPLMode/command_declarations.jl b/src/REPLMode/command_declarations.jl
index a9d9cc3304..b838ae44bd 100644
--- a/src/REPLMode/command_declarations.jl
+++ b/src/REPLMode/command_declarations.jl
@@ -308,11 +308,13 @@ packages have changed causing the current Manifest to be out of sync.
 ],
 PSA[:name => "activate",
     :api => API.activate,
-    :arg_count => 0 => 1,
+    :arg_count => 0 => 2,
     :arg_parser => parse_activate,
     :option_spec => [
         PSA[:name => "shared", :api => :shared => true],
         PSA[:name => "temp", :api => :temp => true],
+        PSA[:name => "test", :api => :target => :test],
+        PSA[:name => "build", :api => :target => :build],
     ],
     :completions => :complete_activate,
     :description => "set the primary environment the package manager manipulates",
@@ -321,6 +323,8 @@ PSA[:name => "activate",
     activate [--shared] path
     activate --temp
     activate - (activates the previously active environment)
+    activate --test (activates the test target within the current environment)
+    activate --build (activates the build target within the current environment)
 
 Activate the environment at the given `path`, or use the first project found in
 `LOAD_PATH` (ignoring `"@"`) if no `path` is specified.
diff --git a/src/Types.jl b/src/Types.jl
index 5f72f49c96..162d47ecd8 100644
--- a/src/Types.jl
+++ b/src/Types.jl
@@ -172,6 +172,7 @@ end
 
 function projectfile_path(env_path::String; strict=false)
     for name in Base.project_names
+        basename(env_path) == name && isfile(env_path) && return env_path
         maybe_file = joinpath(env_path, name)
         isfile(maybe_file) && return maybe_file
     end