feat(nix/readTree): add tests of the traversal logic in README r/2165

This should closely match the documented behaviour. It might still be
missing some edge cases of course.

Change-Id: I5c75fa045d5f3be8cf5eab787a02644500c14522
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2466
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

15 files changed, 95 insertions, 1 deletions

diff --git a/nix/readTree/tests/default.nix b/nix/readTree/tests/default.nix
index e591dc9fe94d..676cc9e6d988 100644
--- a/nix/readTree/tests/default.nix
+++ b/nix/readTree/tests/default.nix
@@ -10,7 +10,7 @@ let
 
   tree-ex = depot.nix.readTree {} ./test-example;
 
-  example = it "corresponds to the example" [
+  example = it "corresponds to the README example" [
     (assertEq "third_party attrset"
       (lib.isAttrs tree-ex.third_party
       && (! lib.isDerivation tree-ex.third_party))
@@ -32,6 +32,54 @@ let
       "roquefort")
   ];
 
+  tree-tl = depot.nix.readTree {} ./test-tree-traversal;
+
+  traversal-logic = it "corresponds to the traversal logic in the README" [
+    (assertEq "skip subtree default.nix is read"
+      tree-tl.skip-subtree.but
+      "the default.nix is still read")
+    (assertEq "skip subtree a/default.nix is skipped"
+      (tree-tl.skip-subtree ? a)
+      false)
+    (assertEq "skip subtree b/c.nix is skipped"
+      (tree-tl.skip-subtree ? b)
+      false)
+    (assertEq "skip subtree a/default.nix would be read without .skip-subtree"
+      (tree-tl.no-skip-subtree.a)
+      "am I subtree yet?")
+    (assertEq "skip subtree b/c.nix would be read without .skip-subtree"
+      (tree-tl.no-skip-subtree.b.c)
+      "cool")
+
+    (assertEq "default.nix attrset is merged with siblings"
+      tree-tl.default-nix.no
+      "siblings should be read")
+    (assertEq "default.nix means sibling isn’t read"
+      (tree-tl.default-nix ? sibling)
+      false)
+    (assertEq "default.nix means subdirs are still read and merged into default.nix"
+      (tree-tl.default-nix.subdir.a)
+      "but I’m picked up")
+
+    (assertEq "default.nix can be not an attrset"
+      tree-tl.default-nix.no-merge
+      "I’m not merged with any children")
+    (assertEq "default.nix is not an attrset -> children are not merged"
+      (tree-tl.default-nix.no-merge ? subdir)
+      false)
+
+    (assertEq "default.nix can contain a derivation"
+      (lib.isDerivation tree-tl.default-nix.can-be-drv)
+      true)
+    (assertEq "Even if default.nix is a derivation, children are traversed and merged"
+      tree-tl.default-nix.can-be-drv.subdir.a
+      "Picked up through the drv")
+    (assertEq "default.nix drv is not changed by readTree"
+      tree-tl.default-nix.can-be-drv
+      (import ./test-tree-traversal/default-nix/can-be-drv/default.nix {}))
+  ];
+
 in runTestsuite "readTree" [
   example
+  traversal-logic
 ]
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/default.nix b/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/default.nix
new file mode 100644
index 000000000000..95d13d3c2750
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/default.nix
@@ -0,0 +1,7 @@
+{ ... }:
+derivation {
+  name = "im-a-drv";
+  system = builtins.currentSystem;
+  builder = "/bin/sh";
+  args = [ "-c" ''echo "" > $out'' ];
+}
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/subdir/a.nix b/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/subdir/a.nix
new file mode 100644
index 000000000000..2ee2d648f042
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/can-be-drv/subdir/a.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"Picked up through the drv"
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/default.nix b/nix/readTree/tests/test-tree-traversal/default-nix/default.nix
new file mode 100644
index 000000000000..6003b5398305
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/default.nix
@@ -0,0 +1,5 @@
+{ ... }:
+
+{
+  no = "siblings should be read";
+}
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/no-merge/default.nix b/nix/readTree/tests/test-tree-traversal/default-nix/no-merge/default.nix
new file mode 100644
index 000000000000..c469533fbe5b
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/no-merge/default.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"I’m not merged with any children"
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/no-merge/subdir/a.nix b/nix/readTree/tests/test-tree-traversal/default-nix/no-merge/subdir/a.nix
new file mode 100644
index 000000000000..2008c2d2411f
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/no-merge/subdir/a.nix
@@ -0,0 +1 @@
+"not accessible since parent default.nix is not an attrset"
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/sibling.nix b/nix/readTree/tests/test-tree-traversal/default-nix/sibling.nix
new file mode 100644
index 000000000000..8c57f2c16137
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/sibling.nix
@@ -0,0 +1 @@
+"I’m left alone"
diff --git a/nix/readTree/tests/test-tree-traversal/default-nix/subdir/a.nix b/nix/readTree/tests/test-tree-traversal/default-nix/subdir/a.nix
new file mode 100644
index 000000000000..cf0ac2c8f3cf
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/default-nix/subdir/a.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"but I’m picked up"
diff --git a/nix/readTree/tests/test-tree-traversal/no-skip-subtree/a/default.nix b/nix/readTree/tests/test-tree-traversal/no-skip-subtree/a/default.nix
new file mode 100644
index 000000000000..a586ce534ce2
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/no-skip-subtree/a/default.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"am I subtree yet?"
diff --git a/nix/readTree/tests/test-tree-traversal/no-skip-subtree/b/c.nix b/nix/readTree/tests/test-tree-traversal/no-skip-subtree/b/c.nix
new file mode 100644
index 000000000000..06216c417be9
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/no-skip-subtree/b/c.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"cool"
diff --git a/nix/readTree/tests/test-tree-traversal/no-skip-subtree/default.nix b/nix/readTree/tests/test-tree-traversal/no-skip-subtree/default.nix
new file mode 100644
index 000000000000..3d9f241cddb5
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/no-skip-subtree/default.nix
@@ -0,0 +1,5 @@
+{ ... }:
+
+{
+  but = "the default.nix is still read";
+}
diff --git a/nix/readTree/tests/test-tree-traversal/skip-subtree/.skip-subtree b/nix/readTree/tests/test-tree-traversal/skip-subtree/.skip-subtree
new file mode 100644
index 000000000000..87271ba5e101
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/skip-subtree/.skip-subtree
@@ -0,0 +1 @@
+this file makes subdirs be skipped, I hope
diff --git a/nix/readTree/tests/test-tree-traversal/skip-subtree/a/default.nix b/nix/readTree/tests/test-tree-traversal/skip-subtree/a/default.nix
new file mode 100644
index 000000000000..a586ce534ce2
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/skip-subtree/a/default.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"am I subtree yet?"
diff --git a/nix/readTree/tests/test-tree-traversal/skip-subtree/b/c.nix b/nix/readTree/tests/test-tree-traversal/skip-subtree/b/c.nix
new file mode 100644
index 000000000000..06216c417be9
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/skip-subtree/b/c.nix
@@ -0,0 +1,3 @@
+{ ... }:
+
+"cool"
diff --git a/nix/readTree/tests/test-tree-traversal/skip-subtree/default.nix b/nix/readTree/tests/test-tree-traversal/skip-subtree/default.nix
new file mode 100644
index 000000000000..3d9f241cddb5
--- /dev/null
+++ b/nix/readTree/tests/test-tree-traversal/skip-subtree/default.nix
@@ -0,0 +1,5 @@
+{ ... }:
+
+{
+  but = "the default.nix is still read";
+}