add hijack

Author: rfourquet

README.md

@@ -174,3 +174,13 @@ function recursive_includet(filename)
     end
 end
 ```
+
+### Working with test files which use Test
+
+It's sometimes possible to use `ReTest` features on a test code base which uses `Test`:
+- if you have a package `Package`, you can try `ReTest.hijack(Package)`, which will define
+a `PackageTests` module when successful, on which you can call `retest`.
+- if you have a test file `"testfile.jl"`, try `ReTest.hijack("testfile.jl")`
+(this will define a fresh module like above).
+
+Check out the docstring of `ReTest.hijack` for more details.

src/ReTest.jl

@@ -789,6 +789,70 @@ function dryrun(mod::Module, ts::TestsetExpr, rx::Regex, align::Int=0, parentsub
     end
 end
 
+## hijack ####################################################################
+
+"""
+    ReTest.hijack(source, [modname]; parentmodule::Module=Main)
+
+Given test files defined in `source` using the `Test` package,
+try to load them by replacing `Test` with `ReTest`, wrapping them in a module `modname`
+defined withing `parentmodule`. If successful, the newly created module `modname` is
+returned and `modname.runtests()` should be callable.
+
+If `source::AbstractString`, then it's interpreted as the top level test file
+(possibly including other files).
+If `source::Module`, then it's interpreted as the name of a package, and the
+"test/runtests.jl" file from this package is loaded. In this case, `modname`
+defaults to `Symbol(source, :Tests)`.
+"""
+function hijack end
+
+function hijack(path::AbstractString, modname=nothing; parentmodule::Module=Main)
+    if modname === nothing
+        modname = :TestMod
+        i = 1
+        while hasproperty(parentmodule, modname)
+            modname = Symbol(:TestMod, i)
+            i += 1
+        end
+    end
+    modname = Symbol(modname)
+
+    newmod = @eval parentmodule module $modname
+                                    using ReTest # for files which don't have `using Test`
+                                    include($substitue_retest!, $path)
+                                end
+    newmod
+end
+
+function hijack(packagemod::Module, modname=nothing; parentmodule::Module=Main)
+    path = joinpath(dirname(dirname(pathof(packagemod))), "test", "runtests.jl")
+    if modname === nothing
+        modname = Symbol(packagemod, :Tests)
+    end
+    hijack(path, modname, parentmodule=parentmodule)
+end
+
+function substitue_retest!(ex)
+    if Meta.isexpr(ex, :using)
+        for used in ex.args
+            if Meta.isexpr(used, :., 1) && used.args[1] == :ReTest
+                throw(ArgumentError("ReTest is already used"))
+            elseif Meta.isexpr(used, :., 1) && used.args[1] == :Test
+                used.args[1] = :ReTest
+            end
+        end
+    elseif Meta.isexpr(ex, :call) && ex.args[1] == :include
+        if length(ex.args) > 2
+            throw(ArgumentError("cannot handle include with two arguments"))
+        else
+            insert!(ex.args, 2, substitue_retest!)
+        end
+    end
+    ex
+end
+
+
 module ReTestTest
 
 using ..ReTest