Add tests for `enter` command

test/114_accept_enter.bats

@@ -0,0 +1,66 @@
+load common
+load_fixtures
+status=;output=; #; populated by bats run()
+
+setup() {
+  build_repo
+}
+
+@test "Command 'enter' (SHELL not set)" {
+  echo "
+    When 'enter' command is provided,
+      And SHELL is not set
+        Report error
+        Exit with 1
+  "
+
+  SHELL=
+  export SHELL
+  run "${T_YADM_Y[@]}" enter
+
+  #; validate status and output
+  [ $status -eq 1 ]
+  [[ "$output" =~ does.not.refer.to.an.executable ]]
+}
+
+@test "Command 'enter' (SHELL not executable)" {
+  echo "
+    When 'enter' command is provided,
+      And SHELL is not executable
+        Report error
+        Exit with 1
+  "
+
+  touch "$T_TMP/badshell"
+  SHELL="$T_TMP/badshell"
+  export SHELL
+  run "${T_YADM_Y[@]}" enter
+
+  #; validate status and output
+  [ $status -eq 1 ]
+  [[ "$output" =~ does.not.refer.to.an.executable ]]
+}
+
+@test "Command 'enter' (SHELL executable)" {
+  echo "
+    When 'enter' command is provided,
+      And SHELL is set
+        Execute SHELL command
+        Expose GIT variables
+        Set prompt variables
+        Announce entering/leaving shell
+        Exit with 0
+  "
+
+  SHELL=$(command -v env)
+  export SHELL
+  run "${T_YADM_Y[@]}" enter
+
+  #; validate status and output
+  [ $status -eq 0 ]
+  [[ "$output" =~ GIT_DIR= ]]
+  [[ "$output" =~ PROMPT=yadm.shell ]]
+  [[ "$output" =~ PS1=yadm.shell ]]
+  [[ "$output" =~ Entering.yadm.repo ]]
+  [[ "$output" =~ Leaving.yadm.repo ]]
+}