Make ZIP extract test clearer, add test case where only unzip can be used

test/blackbox-tests/test-cases/pkg/zip-extract-fail.t

@@ -4,12 +4,52 @@ Test the error message when unzip is needed but not installed.
 
   $ make_lockdir
 
+Set up our fake decompressor binaries, they all just copy the file to the
+expected location:
+
+  $ mkdir -p .binaries
+  $ cat > .binaries/gnutar << 'EOF'
+  > #!/usr/bin/env sh
+  > case "$1" in
+  >  --version)
+  >    echo "tar"
+  >  ;;
+  >  *)
+  >    cp "$2" "$4/$(basename "${2%.zip}")"
+  > esac
+  > EOF
+  $ chmod +x .binaries/gnutar
+  $ cat > .binaries/bsdtar << 'EOF'
+  > #!/usr/bin/env sh
+  > case "$1" in
+  >  --version)
+  >    echo "bsdtar"
+  >  ;;
+  >  *)
+  >    cp "$2" "$4/$(basename "${2%.zip}")"
+  > esac
+  > EOF
+  $ chmod +x .binaries/bsdtar
+  $ cat > .binaries/unzip << 'EOF'
+  > #!/usr/bin/env sh
+  > cp "$2" "$4/$(basename "${2%.zip}")"
+  > EOF
+  $ chmod +x .binaries/unzip
+
+Set up a folder that we will inject as fake PATH:
+
   $ mkdir -p .fakebin
   $ ln -s $(which dune) .fakebin/dune
   $ ln -s $(which sh) .fakebin/sh
   $ ln -s $(which cp) .fakebin/cp
+  $ show_path() {
+  >   ls .fakebin | sort | xargs
+  > }
 
-  $ echo "random" >> test.txt.zip
+Our "compressed" ZIP file is not compressed (as the extraction is just a copy),
+but does have a .zip suffix:
+
+  $ echo "random" > test.txt.zip
 
   $ makepkg() {
   > make_lockpkg $1 <<EOF
@@ -23,76 +63,51 @@ Test the error message when unzip is needed but not installed.
   $ makepkg foo
 
 Build the package in an environment without unzip, or tar, or bsdtar.
-  $ PATH=.fakebin build_pkg foo 2>&1 | grep '^Error:' -A 3
+
+(NOTE: We wrap `(PATH=.fakebin foo)` in parens, otherwise the value of the PATH
+variable can escape to subseqent shell invocations on MacOS.)
+
+  $ show_path
+  cp dune sh
+  $ (PATH=.fakebin build_pkg foo 2>&1 | grep '^Error:' -A 3)
   Error: No program found to extract zip file. Tried:
   - unzip
   - bsdtar
   - tar
 
-Build with only tar that doesn't work, not bsdtar or unzip, it should still fail to build
+Build with only GNU tar that can't extract ZIP archives:
 
-  $ cat > .fakebin/tar << 'EOF'
-  > #!/usr/bin/env sh
-  > case $1 in
-  >  --version)
-  >    echo "tar"
-  >  ;;
-  >  *)
-  >    cp "$2" "$4/$(basename "${2%.zip}")"
-  > esac
-  > EOF
-  $ chmod +x .fakebin/tar
-  $ PATH=.fakebin build_pkg foo 2>&1 | grep '^Error:' -A 3
+  $ ln -s .binaries/gnutar .fakebin/tar
+  $ show_path
+  cp dune sh tar
+  $ (PATH=.fakebin build_pkg foo 2>&1 | grep '^Error:' -A 3)
   Error: No program found to extract zip file. Tried:
   - unzip
   - bsdtar
   - tar
 
-Build with only tar that works, not bsdtar or unzip, it should work
+Build with bsdtar that can extract ZIP archives, without unzip. It should work:
 
-(NOTE: We wrap `(PATH=.fakebin foo)` in parens, otherwise the value of the PATH
-variable can escape to subseqent shell invocations on MacOS.)
-
-  $ cat > .fakebin/tar << 'EOF'
-  > #!/usr/bin/env sh
-  > case $1 in
-  >  --version)
-  >    echo "bsdtar"
-  >  ;;
-  >  *)
-  >    cp "$2" "$4/$(basename "${2%.zip}")"
-  > esac
-  > EOF
-  $ chmod +x .fakebin/tar
+  $ rm .fakebin/tar
+  $ cp .binaries/bsdtar .fakebin/tar
+  $ show_path
+  cp dune sh tar
   $ (PATH=.fakebin build_pkg foo)
 
 Build the package with bsdtar and tar. Now our fake bsdtar will get picked up
-and built.
+and used to extract:
 
-  $ cat > .fakebin/bsdtar << 'EOF'
-  > #!/usr/bin/env sh
-  > case $1 in
-  >  --version)
-  >    echo "bsdtar"
-  >  ;;
-  >  *)
-  >    cp "$2" "$4/$(basename "${2%.zip}")"
-  > esac
-  > EOF
-  $ chmod +x .fakebin/bsdtar
+  $ rm .fakebin/tar
+  $ ln -s .binaries/gnutar .fakebin/tar
+  $ ln -s .binaries/bsdtar .fakebin/bsdtar
+  $ show_path
+  bsdtar cp dune sh tar
   $ (PATH=.fakebin build_pkg foo)
 
-Build with unzip
+Build with unzip only:
 
-  $ cat > .fakebin/unzip << 'EOF'
-  > #!/usr/bin/env sh
-  > case $1 in
-  >  --version)
-  >    echo "unzip"
-  >  ;;
-  >  *)
-  >    cp "$2" "$4/$(basename "${2%.zip}")"
-  > esac
-  > EOF
-  $ chmod +x .fakebin/unzip
+  $ ln -s .binaries/unzip .fakebin/unzip
+  $ rm .fakebin/bsdtar .fakebin/tar
+  $ show_path
+  cp dune sh unzip
   $ (PATH=.fakebin build_pkg foo)