From 1d1ec85d288e70511272e06d124606543016651c Mon Sep 17 00:00:00 2001
From: yosuke ota <otameshiyo23@gmail.com>
Date: Sat, 10 Oct 2020 08:53:44 +0900
Subject: [PATCH] Fixed false positives when used via argument in
 `vue/no-unused-properties`

---
 lib/rules/no-unused-properties.js       | 100 +++++++++++++++++++++---
 tests/lib/rules/no-unused-properties.js |  89 +++++++++++++++++++++
 2 files changed, 180 insertions(+), 9 deletions(-)

diff --git a/lib/rules/no-unused-properties.js b/lib/rules/no-unused-properties.js
index 23fab4424..75b56a4ef 100644
--- a/lib/rules/no-unused-properties.js
+++ b/lib/rules/no-unused-properties.js
@@ -578,6 +578,41 @@ module.exports = {
       }
     }
 
+    /**
+     * @param {VueComponentPropertiesContainer} container
+     * @param {UsedProps} baseUseProps
+     */
+    function processUsed(container, baseUseProps) {
+      for (const { usedNames, unknown } of iterateUsedProps(baseUseProps)) {
+        if (unknown) {
+          container.unknown = true
+          return
+        }
+        for (const name of usedNames.names()) {
+          container.usedNames.add(name)
+        }
+      }
+    }
+
+    /**
+     * @param {Expression} node
+     * @returns {Property|null}
+     */
+    function getParentProperty(node) {
+      if (
+        !node.parent ||
+        node.parent.type !== 'Property' ||
+        node.parent.value !== node
+      ) {
+        return null
+      }
+      const property = node.parent
+      if (!property.parent || property.parent.type !== 'ObjectExpression') {
+        return null
+      }
+      return /** @type {Property} */ (property)
+    }
+
     const scriptVisitor = Object.assign(
       {},
       utils.defineVueVisitor(context, {
@@ -629,6 +664,61 @@ module.exports = {
             container.properties.push(prop)
           }
         },
+        /** @param { (FunctionExpression | ArrowFunctionExpression) & { parent: Property }} node */
+        'ObjectExpression > Property > :function[params.length>0]'(
+          node,
+          vueData
+        ) {
+          const property = getParentProperty(node)
+          if (!property) {
+            return
+          }
+          if (property.parent === vueData.node) {
+            if (utils.getStaticPropertyName(property) !== 'data') {
+              return
+            }
+            // check { data: (vm) => vm.prop }
+          } else {
+            const parentProperty = getParentProperty(property.parent)
+            if (!parentProperty) {
+              return
+            }
+            if (parentProperty.parent === vueData.node) {
+              if (utils.getStaticPropertyName(parentProperty) !== 'computed') {
+                return
+              }
+              // check { computed: { foo: (vm) => vm.prop } }
+            } else {
+              const parentParentProperty = getParentProperty(
+                parentProperty.parent
+              )
+              if (!parentParentProperty) {
+                return
+              }
+              if (parentParentProperty.parent === vueData.node) {
+                if (
+                  utils.getStaticPropertyName(parentParentProperty) !==
+                    'computed' ||
+                  utils.getStaticPropertyName(property) !== 'handler'
+                ) {
+                  return
+                }
+                // check { computed: { foo: { handler: (vm) => vm.prop } } }
+              } else {
+                return
+              }
+            }
+          }
+
+          const paramsUsedProps = getParamsUsedProps(node)
+          const usedProps = /** @type {ParamUsedProps} */ (paramsUsedProps.getParam(
+            0
+          ))
+          processUsed(
+            getVueComponentPropertiesContainer(vueData.node),
+            usedProps
+          )
+        },
         onSetupFunctionEnter(node, vueData) {
           const container = getVueComponentPropertiesContainer(vueData.node)
           if (node.params[0]) {
@@ -690,15 +780,7 @@ module.exports = {
           const container = getVueComponentPropertiesContainer(vueData.node)
           const usedProps = extractPatternOrThisProperties(node, context)
 
-          for (const { usedNames, unknown } of iterateUsedProps(usedProps)) {
-            if (unknown) {
-              container.unknown = true
-              return
-            }
-            for (const name of usedNames.names()) {
-              container.usedNames.add(name)
-            }
-          }
+          processUsed(container, usedProps)
         }
       }),
       {
diff --git a/tests/lib/rules/no-unused-properties.js b/tests/lib/rules/no-unused-properties.js
index dffa036f8..78e15c4f8 100644
--- a/tests/lib/rules/no-unused-properties.js
+++ b/tests/lib/rules/no-unused-properties.js
@@ -1078,6 +1078,48 @@ tester.run('no-unused-properties', rule, {
       </script>
       `,
       options: [{ groups: ['props', 'data'] }]
+    },
+    // contexts
+    {
+      filename: 'test.vue',
+      code: `
+      <script>
+        export default {
+          props: ['x'],
+          data: ({ x }) => ({
+              y: x
+          })
+        };
+      </script>
+      `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <script>
+        export default {
+          props: ['x'],
+          computed: {
+            y: (vm) => vm.x * 2
+          }
+        };
+      </script>
+      `
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <script>
+        export default {
+          props: ['x'],
+          computed: {
+            y: {
+              handler: (vm) => vm.x * 2
+            }
+          }
+        };
+      </script>
+      `
     }
   ],
 
@@ -1574,6 +1616,53 @@ tester.run('no-unused-properties', rule, {
       })
       `,
       errors: ["'foo' of property found, but never used."]
+    },
+
+    // contexts
+    {
+      filename: 'test.vue',
+      code: `
+      <script>
+        export default {
+          props: ['x'],
+          data: () => ({
+              y: x
+          })
+        };
+      </script>
+      `,
+      errors: ["'x' of property found, but never used."]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <script>
+        export default {
+          props: ['x'],
+          computed: {
+            [(vm) => vm.x * 2]: y
+          }
+        };
+      </script>
+      `,
+      errors: ["'x' of property found, but never used."]
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <script>
+        export default {
+          props: ['x'],
+          computed: {
+            y: {
+              handler: (vm) => vm.z * 2,
+              deep: (vm) => vm.x * 2
+            }
+          }
+        };
+      </script>
+      `,
+      errors: ["'x' of property found, but never used."]
     }
   ]
 })