add bats test for diff with raw template

Author: troyready

tests/suite.bats

@@ -713,6 +713,45 @@ EOF
   assert_has_line "${STACKER_NAMESPACE}-vpc: complete (stack destroyed)"
 }
 
+@test "stacker diff - raw template" {
+  needs_aws
+
+  config1() {
+    cat <<EOF
+namespace: ${STACKER_NAMESPACE}
+stacks:
+  - name: vpc
+    template_path: ../stacker/tests/fixtures/cfn_template.yaml
+    variables:
+      Param1: foobar
+EOF
+  }
+
+  config2() {
+    cat <<EOF
+namespace: ${STACKER_NAMESPACE}
+stacks:
+  - name: vpc
+    template_path: ../stacker/tests/fixtures/cfn_template.yaml
+    variables:
+      Param1: newbar
+EOF
+  }
+
+  teardown() {
+    stacker destroy --force <(config1)
+  }
+
+  # Create the new stacks.
+  stacker build <(config1)
+  assert "$status" -eq 0
+
+  stacker diff <(config2)
+  assert "$status" -eq 0
+  assert_has_line "\-Param1 = foobar"
+  assert_has_line "+Param1 = newbar"
+}
+
 @test "stacker build - no parallelism" {
   needs_aws