Expose buildpack detection as a command

.editorconfig

@@ -7,11 +7,9 @@ end_of_line = lf
 insert_final_newline = true
 charset = utf-8
 trim_trailing_whitespace = true
+indent_style = space
+indent_size = 2
 
 [*.go]
 indent_style = tab
 indent_size = 4
-
-[contrib/post-install]
-indent_size = 2
-indent_style = space

.gitignore

@@ -4,3 +4,4 @@ build
 include/cedarish.txt
 include/buildpacks.txt
 bindata.go
+.idea/

Makefile

@@ -126,7 +126,7 @@ clean:
 
 deps: bindata.go
 	docker pull heroku/heroku:24-build
-	cd / && go get -u github.com/progrium/basht/...
+	cd / && go install github.com/progrium/basht/...
 	$(MAKE) bindata.go
 	go get || true
 

README.md

@@ -35,6 +35,7 @@ $ herokuish
 Available commands:
   buildpack                Use and install buildpacks
     build                    Build an application using installed buildpacks
+    detect                   Detect buildpack to use for an application
     install                  Install buildpack from Git URL and optional committish
     list                     List installed buildpacks
     test                     Build and run tests for an application using installed buildpacks

include/buildpack.bash

@@ -70,6 +70,14 @@ _select-buildpack() {
   fi
 }
 
+buildpack-detect() {
+  declare desc="Detect suitable buildpack for an application"
+  ensure-paths
+  [[ "$USER" ]] || randomize-unprivileged
+  buildpack-setup >/dev/null
+  _select-buildpack
+}
+
 buildpack-build() {
   declare desc="Build an application using installed buildpacks"
   ensure-paths

include/herokuish.bash

@@ -133,6 +133,7 @@ main() {
   cmd-export buildpack-install
   cmd-export buildpack-list
   cmd-export buildpack-test
+  cmd-export buildpack-detect
 
   cmd-export-ns slug "Manage application slugs"
   cmd-export slug-import

tests/functional/tests.sh

@@ -48,3 +48,48 @@ T_generate-slug() {
 		herokuish slug generate
 		tar tzf /tmp/slug.tgz"
 }
+
+T_buildpack-detect-default() {
+  herokuish-test "buildpack-detect-default" "
+    set -e
+    unset BUILDPACK_URL
+    export buildpack_path=/tmp/buildpacks
+    export build_path=/tmp/app
+    export unprivileged_user=\$(whoami)
+    export unprivileged_group=\$(id -gn)
+
+    rm -rf \$buildpack_path && mkdir -p \$buildpack_path
+
+    mkdir -p \$buildpack_path/00_buildpack-ruby/bin
+    {
+      echo '#!/usr/bin/env bash'
+      echo 'echo Ruby'
+      echo 'exit 0'
+    } > \$buildpack_path/00_buildpack-ruby/bin/detect
+    chmod +x \$buildpack_path/00_buildpack-ruby/bin/detect
+
+    herokuish buildpack detect | grep 'Ruby app detected'
+  "
+}
+
+T_buildpack-detect-fail() {
+  herokuish-test "buildpack-detect-fail" "
+    set -e
+    unset BUILDPACK_URL
+    export buildpack_path=/tmp/buildpacks
+    export build_path=/tmp/app
+    export unprivileged_user=\$(whoami)
+    export unprivileged_group=\$(id -gn)
+
+    rm -rf \$buildpack_path && mkdir -p \$buildpack_path
+
+    mkdir -p \$buildpack_path/00_buildpack-fail/bin
+    {
+      echo '#!/usr/bin/env bash'
+      echo 'exit 1'
+    } > \$buildpack_path/00_buildpack-fail/bin/detect
+    chmod +x \$buildpack_path/00_buildpack-fail/bin/detect
+
+    herokuish buildpack detect 2>&1 | grep 'Unable to select a buildpack'
+  "
+}