tests/template: Skip tests if programs are missing

Most of the test cases will now be skipped if any of the required
programs are missing, rather than failing and requiring the user to
investigate.

Whereas `skip_if_system_missing` will skip a test case if any of the
specified programs are missing, `skip_if_none_present_on_system` will
skip a test case only if all of the programs are missing. I'll move it
to `lib/bats/helpers` in a future commit.

Author: mbland

tests/template.bats

@@ -75,6 +75,25 @@ assert_go_core_unpacked() {
   restore_bats_shell_options "$result"
 }
 
+# Skips the current test if zero of the listed system programs are present.
+#
+# Arguments:
+#   $@:  System programs of which at least one must be present to run the test
+skip_if_none_present_on_system() {
+  local missing
+
+  if ! command -v "$@" >/dev/null; then
+    if [[ "$#" -eq '1' ]]; then
+      skip "$1 isn't installed on the system"
+    elif [[ "$#" -eq '2' ]]; then
+      skip "Neither $1 nor $2 are installed on the system"
+    else
+      printf -v missing '%s, ' "${@:1:$(($# - 1))}"
+      skip "None of ${missing% } or ${@:$#} are installed on the system"
+    fi
+  fi
+}
+
 # Converts a Unix path or 'file://' URL to a Git for Windows native path.
 #
 # This is useful when passing file paths or URLs to native programs on Git for
@@ -202,6 +221,8 @@ run_with_download_program() {
 }
 
 @test "$SUITE: download $GO_SCRIPT_BASH_VERSION from $FULL_DOWNLOAD_URL" {
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'tar'
   create_fake_tarball_if_not_using_real_url
   run "$TEST_GO_ROOTDIR/go-template"
 
@@ -215,6 +236,7 @@ run_with_download_program() {
 }
 
 @test "$SUITE: download locally using curl" {
+  skip_if_system_missing 'tar'
   run_with_download_program 'curl'
   assert_output_matches "Downloading framework from '$NATIVE_LOCAL_URL'\.\.\."
   assert_output_matches "Download of '$NATIVE_LOCAL_URL' successful."$'\n\n'
@@ -223,6 +245,7 @@ run_with_download_program() {
 }
 
 @test "$SUITE: download locally using fetch" {
+  skip_if_system_missing 'tar'
   run_with_download_program 'fetch'
   assert_output_matches "Downloading framework from '$NATIVE_LOCAL_URL'\.\.\."
   assert_output_matches "Download of '$NATIVE_LOCAL_URL' successful."$'\n\n'
@@ -231,6 +254,7 @@ run_with_download_program() {
 }
 
 @test "$SUITE: download locally using cat" {
+  skip_if_system_missing 'tar'
   # We'll actually use `cat` with `file://` URLs, since `wget` only supports
   # HTTP, HTTPS, and FTP.
   run_with_download_program 'cat'
@@ -241,6 +265,7 @@ run_with_download_program() {
 }
 
 @test "$SUITE: download locally using wget" {
+  skip_if_system_missing 'tar'
   # As mentioned in the above test case, we'll actually use `cat` with `file://`
   # URLs, but we're simulating `wget` by pretending `cat` doesn't exist.
   run_with_download_program 'wget'
@@ -252,6 +277,8 @@ run_with_download_program() {
 
 @test "$SUITE: download into nonstandard GO_SCRIPTS_DIR" {
   local core_dir="$TEST_GO_ROOTDIR/foobar"
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'tar'
   create_fake_tarball_if_not_using_real_url
 
   # Create a command script in the normal `TEST_GO_SCRIPTS_DIR`.
@@ -265,6 +292,8 @@ run_with_download_program() {
 }
 
 @test "$SUITE: download uses existing GO_SCRIPTS_DIR" {
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'tar'
   create_fake_tarball_if_not_using_real_url
   mkdir -p "$TEST_GO_SCRIPTS_DIR"
   stub_program_in_path mkdir "exit 1"
@@ -280,6 +309,9 @@ run_with_download_program() {
 @test "$SUITE: fail to download a nonexistent repo" {
   local url='https://bogus-url-that-does-not-exist'
   local repo='bogus-repo-that-does-not-exist'
+
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'git'
   GO_SCRIPT_BASH_DOWNLOAD_URL="$url" GO_SCRIPT_BASH_REPO_URL="$repo" \
     run "$TEST_GO_ROOTDIR/go-template"
   assert_failure
@@ -294,6 +326,9 @@ run_with_download_program() {
 @test "$SUITE: fail to download a nonexistent version" {
   local url="$GO_SCRIPT_BASH_DOWNLOAD_URL/vnonexistent.tar.gz"
   local branch='vnonexistent'
+
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'git'
   GO_SCRIPT_BASH_VERSION="$branch" run "$TEST_GO_ROOTDIR/go-template"
   assert_failure
   assert_output_matches 'Using git clone as fallback'
@@ -307,6 +342,7 @@ run_with_download_program() {
 @test "$SUITE: use git clone if GO_SCRIPT_BASH_DOWNLOAD_URL lacks a protocol" {
   local url='bogus-url-with-no-protocol'
 
+  skip_if_system_missing 'git'
   GO_SCRIPT_BASH_DOWNLOAD_URL="$url" run "$TEST_GO_ROOTDIR/go-template"
 
   assert_output_matches "GO_SCRIPT_BASH_DOWNLOAD_URL has no protocol: $url"
@@ -325,6 +361,7 @@ run_with_download_program() {
 }
 
 @test "$SUITE: fail to find download program uses git clone" {
+  skip_if_system_missing 'git'
   PATH="$BATS_TEST_BINDIR" run "$BASH" "$TEST_GO_ROOTDIR/go-template"
 
   assert_output_matches "Failed to find cURL, wget, or fetch"
@@ -335,7 +372,8 @@ run_with_download_program() {
 }
 
 @test "$SUITE: fail to find tar uses git clone" {
-  # If none of these are installed on the system, the test will fail.
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'git'
   create_forwarding_script 'curl'
   create_forwarding_script 'wget'
   create_forwarding_script 'fetch'
@@ -350,6 +388,8 @@ run_with_download_program() {
 }
 
 @test "$SUITE: fail to create directory uses git clone" {
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'git' 'tar'
   create_fake_tarball_if_not_using_real_url
   stub_program_in_path mkdir "exit 1"
   run "$TEST_GO_ROOTDIR/go-template"
@@ -371,6 +411,8 @@ run_with_download_program() {
 @test "$SUITE: fail to move extracted directory uses git clone" {
   local target="$TEST_GO_SCRIPTS_DIR/go-script-bash"
 
+  skip_if_none_present_on_system 'curl' 'fetch' 'wget'
+  skip_if_system_missing 'git' 'tar'
   create_fake_tarball_if_not_using_real_url
   stub_program_in_path mv "exit 1"
   run "$TEST_GO_ROOTDIR/go-template"