2 files changed, 103 insertions, 0 deletions
diff --git a/tests/fixtures.sh b/tests/fixtures.sh
index 9608fcd..9813c8f 100755
--- a/tests/fixtures.sh
+++ b/tests/fixtures.sh
@@ -147,6 +147,75 @@ cat > /fixtures/uselocal/flake.nix <<'NIX'
 NIX
 (cd /fixtures/uselocal && nix flake lock)
 
+# follow: a flake whose input dep draws its input inner from the flake's own
+# input inner, which is inner2, so the lock file records a follows path, and
+# dep's own lock file pins another inner than the flake's.
+mkdir /fixtures/www/src/inner2
+cat > /fixtures/www/src/inner2/flake.nix <<'NIX'
+{ outputs = _: { who = "inner2"; }; }
+NIX
+tarball inner2
+mkdir /fixtures/follow
+cat > /fixtures/follow/flake.nix <<NIX
+{
+  inputs.inner.url = "$url/inner2.tar.gz";
+  inputs.dep.url = "$url/dep.tar.gz";
+  inputs.dep.inputs.inner.follows = "inner";
+  outputs = { dep, ... }: { msg = "follow:\${dep.greeting}"; };
+}
+NIX
+(cd /fixtures/follow && nix flake lock)
+
+# nofollow: a flake that removes an input of its input, so the lock file
+# records an empty follows path.
+mkdir /fixtures/nofollow
+cat > /fixtures/nofollow/flake.nix <<NIX
+{
+  inputs.dep.url = "$url/dep.tar.gz";
+  inputs.dep.inputs.inner.follows = "";
+  outputs = _: { msg = "nofollow"; };
+}
+NIX
+(cd /fixtures/nofollow && nix flake lock)
+
+# cyc: a flake whose inputs cyca and cycb follow each other.
+for name in cyca cycb; do
+  other=$(test $name = cyca && echo cycb || echo cyca)
+  mkdir /fixtures/www/src/$name
+  cat > /fixtures/www/src/$name/flake.nix <<NIX
+{
+  inputs.other.url = "$url/$other.tar.gz";
+  outputs = _: { who = "$name"; };
+}
+NIX
+  tarball $name
+done
+mkdir /fixtures/cyc
+cat > /fixtures/cyc/flake.nix <<NIX
+{
+  inputs.a.url = "$url/cyca.tar.gz";
+  inputs.b.url = "$url/cycb.tar.gz";
+  inputs.a.inputs.other.follows = "b";
+  inputs.b.inputs.other.follows = "a";
+  outputs = { a, b, ... }: { msg = "cyc:\${a.who},\${b.who}"; };
+}
+NIX
+(cd /fixtures/cyc && nix flake lock)
+
+# rel: a flake in a Git work tree with an input in a subdirectory, referred
+# to by a relative path.
+mkdir -p /fixtures/rel/lib
+cat > /fixtures/rel/lib/flake.nix <<'NIX'
+{ outputs = _: { who = "lib"; }; }
+NIX
+cat > /fixtures/rel/flake.nix <<'NIX'
+{
+  inputs.lib.url = "path:./lib";
+  outputs = { lib, ... }: { msg = "rel:${lib.who}"; };
+}
+NIX
+(cd /fixtures/rel && nix flake lock && git init -q && commit rel)
+
 # noflake: a directory without flake.nix.
 mkdir /fixtures/noflake
 echo noflake > /fixtures/noflake/README
diff --git a/tests/scenarios.nix b/tests/scenarios.nix
index ef80d05..a738eca 100644
--- a/tests/scenarios.nix
+++ b/tests/scenarios.nix
@@ -774,6 +774,40 @@ assert !(krops.isLocalTarget (targets.remote "/"));
         '';
       };
     })
+    (s "follows-empty" {
+      phases = twice {
+        sources.x.flake = { flake = "/fixtures/nofollow"; fetchOnTarget = true; };
+        check = checkFlake { attr = "msg"; expected = "nofollow"; };
+      };
+    })
+    (s "follows-cycle" {
+      phases = twice {
+        sources.x.flake = { flake = "/fixtures/cyc"; fetchOnTarget = true; };
+        check = checkFlake { attr = "msg"; expected = "cyc:cyca,cycb"; };
+      };
+    })
+    # Names resolve through the parent's lock file, so dep/inner is the
+    # parent's inner, which dep's inner follows.
+    (s "follows-name" {
+      phases = twice {
+        sources.x.flake-input = { flake = "/fixtures/follow"; name = "dep/inner"; inherit fetchOnTarget; };
+        check = checkFlake { attr = "who"; expected = "inner2"; };
+      };
+    })
+    # The delivered input comes with the inputs its own lock file pins, which
+    # evaluating it needs, not with the parent's inner, which it follows there.
+    (s "follows-closure" {
+      phases = twice {
+        sources.x.flake-input = { flake = "/fixtures/follow"; name = "dep"; inherit fetchOnTarget; };
+        check = checkFlake { attr = "greeting"; expected = "dep+inner"; } + roots 1;
+      };
+    })
+    (s "relative-input" {
+      phases = twice {
+        sources.x.flake = { flake = "/fixtures/rel"; fetchOnTarget = true; };
+        check = checkFlake { attr = "msg"; expected = "rel:lib"; };
+      };
+    })
   ] ++ lib.optional (targetKind == "local")
     # The target has the path the input is locked to.
     (s "uselocal" {