Allow concise config for Environments

This commit combines PR [616](github#616) and [646](github#646)

environments.js
Add defensive code to prevent the GitHub API from being called with undefined data.

In the UI, and API an environment can be added with just an name.
  Now, safe-settings permits this as well.
In the UI, and API an environment can be added without variables.
  Now, safe-settings permits this as well.
In the UI, and API an environment can be added without deployment_protection_rules.
  Now, safe-settings permits this as well.

environments.test.js
Add a test case for the scenario when there are zero existing environments
Add a test case for an environment name change
Add a test case inspired by PR 616 which adds 7 new environments with various attributes
Move expect statements out of aftereach() as there is now variability in what is expected across test cases.
  Specifically, when there is no existing environment, that environment should NOT be queried for variables nor deployment_protection_rules

lib/plugins/environments.js

@@ -16,7 +16,11 @@ module.exports = class Environments extends Diffable {
                 });
               }
             })
-          }
+        }
+
+        // Remove 'name' from filtering list so Environments with only a name defined are processed.
+        MergeDeep.NAME_FIELDS.splice(MergeDeep.NAME_FIELDS.indexOf('name'), 1)
+
     }
 
     async find() {
@@ -160,6 +164,7 @@ module.exports = class Environments extends Diffable {
 
         if(variables) {
             let existingVariables = [...existing.variables];
+
             for(let variable of attrs.variables) {
                 const existingVariable = existingVariables.find((_var) => _var.name === variable.name);
                 if(existingVariable) {
@@ -197,6 +202,7 @@ module.exports = class Environments extends Diffable {
 
         if(deployment_protection_rules) {
             let existingRules = [...existing.deployment_protection_rules];
+
             for(let rule of attrs.deployment_protection_rules) {
                 const existingRule = existingRules.find((_rule) => _rule.id === rule.id);
 
@@ -229,13 +235,14 @@ module.exports = class Environments extends Diffable {
             wait_timer: attrs.wait_timer,
             prevent_self_review: attrs.prevent_self_review,
             reviewers: attrs.reviewers,
-            deployment_branch_policy: attrs.deployment_branch_policy === null ? null : {
-                protected_branches: attrs.deployment_branch_policy.protected_branches,
+            deployment_branch_policy: attrs.deployment_branch_policy == null ? null : {
+                protected_branches: !!attrs.deployment_branch_policy.protected_branches,
                 custom_branch_policies: !!attrs.deployment_branch_policy.custom_branch_policies
             }
         });
 
         if(attrs.deployment_branch_policy && attrs.deployment_branch_policy.custom_branch_policies) {
+
             for(let policy of attrs.deployment_branch_policy.custom_branch_policies) {
                 await this.github.request('POST /repos/:org/:repo/environments/:environment_name/deployment-branch-policies', {
                     org: this.repo.owner,
@@ -244,26 +251,34 @@ module.exports = class Environments extends Diffable {
                     name: policy.name
                 });
             }
+
         }
 
+        if(attrs.variables) {
 
-        for(let variable of attrs.variables) {
-            await this.github.request(`POST /repos/:org/:repo/environments/:environment_name/variables`, {
-                org: this.repo.owner,
-                repo: this.repo.repo,
-                environment_name: attrs.name,
-                name: variable.name,
-                value: variable.value
-            });
-        }
+            for(let variable of attrs.variables) {
+                await this.github.request(`POST /repos/:org/:repo/environments/:environment_name/variables`, {
+                    org: this.repo.owner,
+                    repo: this.repo.repo,
+                    environment_name: attrs.name,
+                    name: variable.name,
+                    value: variable.value
+                });
+            }
+
+          }
+
+        if(attrs.deployment_protection_rules) {
+
+            for(let rule of attrs.deployment_protection_rules) {
+                await this.github.request(`POST /repos/:org/:repo/environments/:environment_name/deployment_protection_rules`, {
+                    org: this.repo.owner,
+                    repo: this.repo.repo,
+                    environment_name: attrs.name,
+                    integration_id: rule.app_id
+                });
+            }
 
-        for(let rule of attrs.deployment_protection_rules) {
-            await this.github.request(`POST /repos/:org/:repo/environments/:environment_name/deployment_protection_rules`, {
-                org: this.repo.owner,
-                repo: this.repo.repo,
-                environment_name: attrs.name,
-                integration_id: rule.app_id
-            });
         }
     }