fix(eslint-plugin): handle missing message IDs in eslint v5/v6

packages/eslint-plugin/src/rules/indent.ts

@@ -97,7 +97,10 @@ export default util.createRule<Options, MessageIds>({
     },
     fixable: 'whitespace',
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      wrongIndentation:
+        'Expected indentation of {{expected}} but found {{actual}}.',
+    },
   },
   defaultOptions: [
     // typescript docs and playground use 4 space indent

packages/eslint-plugin/src/rules/init-declarations.ts

@@ -24,7 +24,12 @@ export default createRule<Options, MessageIds>({
       extendsBaseRule: true,
     },
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      initialized:
+        "Variable '{{idName}}' should be initialized on declaration.",
+      notInitialized:
+        "Variable '{{idName}}' should not be initialized on declaration.",
+    },
   },
   defaultOptions: ['always'],
   create(context) {

packages/eslint-plugin/src/rules/keyword-spacing.ts

@@ -17,7 +17,12 @@ export default util.createRule<Options, MessageIds>({
     },
     fixable: 'whitespace',
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      expectedBefore: 'Expected space(s) before "{{value}}".',
+      expectedAfter: 'Expected space(s) after "{{value}}".',
+      unexpectedBefore: 'Unexpected space(s) before "{{value}}".',
+      unexpectedAfter: 'Unexpected space(s) after "{{value}}".',
+    },
   },
   defaultOptions: [{}],
 

packages/eslint-plugin/src/rules/lines-between-class-members.ts

@@ -32,7 +32,10 @@ export default util.createRule<Options, MessageIds>({
     },
     fixable: 'whitespace',
     schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      never: 'Unexpected blank line between class members.',
+      always: 'Expected blank line between class members.',
+    },
   },
   defaultOptions: [
     'always',

packages/eslint-plugin/src/rules/no-invalid-this.ts

@@ -23,7 +23,9 @@ export default createRule<Options, MessageIds>({
       recommended: false,
       extendsBaseRule: true,
     },
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      unexpectedThis: "Unexpected 'this'.",
+    },
     schema: baseRule.meta.schema,
   },
   defaultOptions: [{ capIsConstructor: true }],

packages/eslint-plugin/src/rules/no-magic-numbers.ts

@@ -40,7 +40,10 @@ export default util.createRule<Options, MessageIds>({
         },
       },
     ],
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      useConst: "Number constants declarations must use 'const'.",
+      noMagic: 'No magic number: {{raw}}.',
+    },
   },
   defaultOptions: [
     {

packages/eslint-plugin/src/rules/no-unused-expressions.ts

@@ -19,7 +19,10 @@ export default util.createRule<Options, MessageIds>({
       extendsBaseRule: true,
     },
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      unusedExpression:
+        'Expected an assignment or function call and instead saw an expression.',
+    },
   },
   defaultOptions: [
     {

packages/eslint-plugin/src/rules/no-unused-vars.ts

@@ -21,7 +21,9 @@ export default util.createRule<Options, MessageIds>({
       extendsBaseRule: true,
     },
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      unusedVar: "'{{varName}}' is {{action}} but never used{{additional}}.",
+    },
   },
   defaultOptions: [{}],
   create(context) {

packages/eslint-plugin/src/rules/no-useless-constructor.ts

@@ -54,7 +54,9 @@ export default util.createRule<Options, MessageIds>({
       extendsBaseRule: true,
     },
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      noUselessConstructor: 'Useless constructor.',
+    },
   },
   defaultOptions: [],
   create(context) {

packages/eslint-plugin/src/rules/quotes.ts

@@ -20,7 +20,9 @@ export default util.createRule<Options, MessageIds>({
       extendsBaseRule: true,
     },
     fixable: 'code',
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      wrongQuotes: 'Strings must use {{description}}.',
+    },
     schema: baseRule.meta.schema,
   },
   defaultOptions: [

packages/eslint-plugin/src/rules/semi.ts

@@ -22,7 +22,10 @@ export default util.createRule<Options, MessageIds>({
     },
     fixable: 'code',
     schema: baseRule.meta.schema,
-    messages: baseRule.meta.messages,
+    messages: baseRule.meta.messages ?? {
+      missingSemi: 'Missing semicolon.',
+      extraSemi: 'Extra semicolon.',
+    },
   },
   defaultOptions: [
     'always',