From 5eb76d181223191015fe41d5956c265001b314fd Mon Sep 17 00:00:00 2001
From: Dilum Aluthge <dilum@aluthge.com>
Date: Thu, 26 Nov 2020 20:36:31 -0500
Subject: [PATCH] Fix the `absuri` function to correctly handle relative
 location paths

---
 .github/workflows/ci.yml |  3 +++
 src/URIs.jl              | 17 ++++++++++++++++-
 test/absuri.jl           | 15 +++++++++++++++
 test/runtests.jl         |  1 +
 4 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 test/absuri.jl

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 489ac43..2b8251b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,6 +20,9 @@ jobs:
           - windows-latest
         arch:
           - x64
+        exclude:
+          - os: windows-latest
+            version: 'nightly'
     steps:
       - uses: actions/checkout@v2
       - uses: julia-actions/setup-julia@v1
diff --git a/src/URIs.jl b/src/URIs.jl
index df4d0da..d7bfc31 100644
--- a/src/URIs.jl
+++ b/src/URIs.jl
@@ -455,7 +455,22 @@ function absuri(uri::URI, context::URI)
     @assert !isempty(context.host)
     @assert isempty(uri.port)
 
-    return URI(context; path=uri.path, query=uri.query)
+    if !(context.scheme in ["http", "https"]) || isempty(uri.path) || uri.path[1] == '/'
+        path = String(uri.path)
+    else
+        # > The "Location" header field is used to identify a newly created resource, or to redirect the recipient to a different location for completion of the request.
+        # > The field value consists of a single URI-reference. When it has the form of a relative reference ([RFC3986], Section 4.2), the final value is computed by resolving it against the effective request URI ([RFC3986], Section 5).
+        # Sources:
+        # 1. https://greenbytes.de/tech/webdav/draft-ietf-httpbis-p2-semantics-17.html#header.location
+        # 2. https://web.archive.org/web/20200926022629/https://greenbytes.de/tech/webdav/draft-ietf-httpbis-p2-semantics-17.html
+        # 3. https://www.rfc-editor.org/rfc/rfc3986.html#section-4.2
+        # 4. https://web.archive.org/web/20201106144353/https://www.rfc-editor.org/rfc/rfc3986.html#section-4.2
+        # 5. https://www.rfc-editor.org/rfc/rfc3986.html#section-5
+        # 6. https://web.archive.org/web/20201106144353/https://www.rfc-editor.org/rfc/rfc3986.html#section-5
+        path = String(uristring(normpath(joinpath(URI(; path = context.path), "..", String(uri.path)))))
+    end
+
+    return URI(context; path=path, query=uri.query)
 end
 
 """
diff --git a/test/absuri.jl b/test/absuri.jl
new file mode 100644
index 0000000..f7f5b18
--- /dev/null
+++ b/test/absuri.jl
@@ -0,0 +1,15 @@
+@testset "absuri.jl" begin
+    cases = [
+        ("https://en.wikipedia.org/api/rest_v1/page/summary/Potatoes", "Potato", "https://en.wikipedia.org/api/rest_v1/page/summary/Potato"),
+        ("https://en.wikipedia.org/api/rest_v1/page/summary/Potatoes", "./Potato", "https://en.wikipedia.org/api/rest_v1/page/summary/Potato"),
+        ("https://en.wikipedia.org/api/rest_v1/page/summary/Potatoes", "/foo/bar/baz", "https://en.wikipedia.org/foo/bar/baz"),
+        ("https://en.wikipedia.org/api/rest_v1/page/summary/Potatoes", "https://julialang.org/foo/bar/baz", "https://julialang.org/foo/bar/baz"),
+    ]
+    for case in cases
+        url = case[1]
+        location = case[2]
+        actual_output = URIs.absuri(location, url)
+        expected_output = URIs.URI(case[3])
+        @test actual_output == expected_output
+    end
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index aca9fb8..206640c 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -3,3 +3,4 @@ using Test
 
 include("uri.jl")
 include("url.jl")
+include("absuri.jl")