More execline experiments & testing

Improves the “execline experience” and adds some basic tests.
The idea is that the final result doesn’t use coreutils and provides a
feasible alternative to bash-based tooling.

1 files changed, 94 insertions, 0 deletions

diff --git a/pkgs/profpatsch/testing/default.nix b/pkgs/profpatsch/testing/default.nix
new file mode 100644
index 00000000..55a141d9
--- /dev/null
+++ b/pkgs/profpatsch/testing/default.nix
@@ -0,0 +1,94 @@
+{ stdenv, runCommand, lib
+, runExecline, s6TouchCommand, s6EchoCommand }:
+
+let
+
+  /* Realize drvDep, then return drvOut if that succeds.
+   * This can be used to make drvOut depend on the
+   * build success of drvDep without making drvDep a
+   * dependency of drvOut
+   * => drvOut is not rebuilt if drvDep changes
+   */
+  drvSeq = drvDep: drvOut: drvSeqL [drvDep] drvOut;
+
+  /* TODO DOCS */
+  drvSeqL = drvDeps: drvOut: let
+    drvOutOutputs = drvOut.outputs or ["out"];
+  in
+    runCommand drvOut.name {
+      # we inherit all attributes in order to replicate
+      # the original derivation as much as possible
+      outputs = drvOutOutputs;
+      passthru = drvOut.drvAttrs;
+      preferLocalBuild = true;
+      allowSubstitutes = false;
+      # depend on drvDeps (by putting it in builder context)
+      inherit drvDeps;
+    }
+    # the outputs of the original derivation are replicated
+    # by creating a symlink to the old output path
+    (lib.concatMapStrings (output: ''
+      target=${lib.escapeShellArg drvOut.${output}}
+      # if the target is already a symlink, follow it until it’s not;
+      # this is done to prevent too many dereferences
+      target=$(readlink -e "$target")
+      # link to the output
+      ln -s "$target" "${"$"}${output}"
+    '') drvOutOutputs);
+
+  /* Takes a derivation and an attribute set of
+   * test names to tests.
+   * Tests can be constructed by calling test
+   * functions like `bashTest` or `execlineTest`.
+   * They generally take scripts that
+   * is not sucessful and succeed otherwise.
+   */
+  withTests = tests: drv:
+    assert lib.isDerivation drv; # drv needs to be a derivation!
+    let testDrvs = lib.mapAttrsToList
+          (testName: testFun: testFun {
+            drvName = "${drv.name}-test-${testName}";
+          }) tests;
+    in drvSeqL testDrvs drv;
+
+  # /* Constructs a test from a bash script.
+  #  * The test will fail if the bash script exits
+  #  * with an exit code other than 0. */
+  # bashTest = testScript: { drvName }:
+  #   runCommand drvName {
+  #     preferLocalBuild = true;
+  #     allowSubstitutes = false;
+  #   } ''
+  #     ${testScript}
+  #     touch "$out"
+  #   '';
+
+  # /* Constructs a test from an execline script.
+  #  * The test will fail if the bash script exits
+  #  * with an exit code other than 0. */
+  # execlineTest = testScript: { drvName }:
+  #   runExecline {
+  #     name = drvName;
+  #     execline = testScript;
+  #     builderWrapper = runExecline {
+  #       name = "touch-out";
+  #       execline = ''
+  #         importas -i out out
+  #         ifte
+  #           # if $@ succeeds, $out is touched
+  #           { ${s6TouchCommand} $out }
+  #           # otherwise we return the exit code
+  #           { importas exit ?
+  #             ${s6EchoCommand} $exit }
+  #           # condition
+  #           $@
+  #       '';
+  #     derivationArgs = {
+  #       preferLocalBuild = true;
+  #       allowSubstitutes = false;
+  #     };
+  #   };
+  # };
+
+in
+  { inherit drvSeq drvSeqL withTests; }